nds32: fix build failure caused by page table folding updates

The commit 7c2763c4 ("nds32: use pgtable-nopmd instead of
4level-fixup") missed the pmd_off_k() macro which caused the following
build error:

  CC      arch/nds32/mm/highmem.o
In file included from arch/nds32/include/asm/page.h:57,
                 from include/linux/mm_types_task.h:16,
                 from include/linux/mm_types.h:5,
                 from include/linux/mmzone.h:21,
                 from include/linux/gfp.h:6,
                 from include/linux/xarray.h:14,
                 from include/linux/radix-tree.h:18,
                 from include/linux/fs.h:15,
                 from include/linux/highmem.h:5,
                 from arch/nds32/mm/highmem.c:5:
arch/nds32/mm/highmem.c: In function 'kmap_atomic':
arch/nds32/include/asm/pgtable.h:360:44: error: passing argument 1 of 'pmd_offset' from incompatible pointer type [-Werror=incompatible-pointer-types]
 #define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))
                                 ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
arch/nds32/include/asm/memory.h:33:29: note: in definition of macro '__phys_to_virt'
 #define __phys_to_virt(x) ((x) - PHYS_OFFSET + PAGE_OFFSET)
                             ^
arch/nds32/include/asm/pgtable.h:193:55: note: in expansion of macro '__va'
 #define pmd_page_kernel(pmd)         ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
                                                       ^~~~
include/asm-generic/pgtable-nop4d.h:41:24: note: in expansion of macro 'pgd_val'
 #define p4d_val(x)    (pgd_val((x).pgd))
                        ^~~~~~~
include/asm-generic/pgtable-nopud.h:50:24: note: in expansion of macro 'p4d_val'
 #define pud_val(x)    (p4d_val((x).p4d))
                        ^~~~~~~
include/asm-generic/pgtable-nopmd.h:49:24: note: in expansion of macro 'pud_val'
 #define pmd_val(x)    (pud_val((x).pud))
                        ^~~~~~~
arch/nds32/include/asm/pgtable.h:193:60: note: in expansion of macro 'pmd_val'
 #define pmd_page_kernel(pmd)         ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
                                                            ^~~~~~~
arch/nds32/include/asm/pgtable.h:190:56: note: in expansion of macro 'pmd_page_kernel'
 #define pte_offset_kernel(dir, address)      ((pte_t *)pmd_page_kernel(*(dir)) + pte_index(address))
                                                        ^~~~~~~~~~~~~~~
arch/nds32/mm/highmem.c:52:9: note: in expansion of macro 'pte_offset_kernel'
  ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
         ^~~~~~~~~~~~~~~~~
arch/nds32/include/asm/pgtable.h:362:33: note: in expansion of macro 'pgd_offset'
 #define pgd_offset_k(addr)      pgd_offset(&init_mm, addr)
                                 ^~~~~~~~~~
arch/nds32/include/asm/pgtable.h:198:39: note: in expansion of macro 'pgd_offset_k'
 #define pmd_off_k(address) pmd_offset(pgd_offset_k(address), address)
                                       ^~~~~~~~~~~~
arch/nds32/mm/highmem.c:52:27: note: in expansion of macro 'pmd_off_k'
  ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
                           ^~~~~~~~~
In file included from arch/nds32/include/asm/pgtable.h:7,
                 from include/linux/mm.h:99,
                 from include/linux/highmem.h:8,
                 from arch/nds32/mm/highmem.c:5:
include/asm-generic/pgtable-nopmd.h:44:42: note: expected 'pud_t *' {aka 'struct <anonymous> *'} but argument is of type 'pgd_t *' {aka 'long unsigned int *'}
 static inline pmd_t * pmd_offset(pud_t * pud, unsigned long address)
                                  ~~~~~~~~^~~
In file included from arch/nds32/include/asm/page.h:57,
                 from include/linux/mm_types_task.h:16,
                 from include/linux/mm_types.h:5,
                 from include/linux/mmzone.h:21,
                 from include/linux/gfp.h:6,
                 from include/linux/xarray.h:14,
                 from include/linux/radix-tree.h:18,
                 from include/linux/fs.h:15,
                 from include/linux/highmem.h:5,
                 from arch/nds32/mm/highmem.c:5:

Updating the pmd_off_k() macro to use the correct page table unfolding
fixes the issue.

Fixes: 7c2763c4 ("nds32: use pgtable-nopmd instead of 4level-fixup")
Link: https://lore.kernel.org/lkml/201912212139.yptX8CsV%25lkp@intel.com/Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Greentime Hu <green.hu@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/nds32/include/asm/pgtable.h

@@ -195,7 +195,7 @@ extern void paging_init(void);
 #define pte_unmap(pte)		do { } while (0)
 #define pte_unmap_nested(pte)	do { } while (0)
 
-#define pmd_off_k(address)	pmd_offset(pgd_offset_k(address), address)
+#define pmd_off_k(address)	pmd_offset(pud_offset(p4d_offset(pgd_offset_k(address), (address)), (address)), (address))
 
 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 /*