RISC-V: Fix building error when CONFIG_SPARSEMEM_MANUAL=y

Fix a build break by adjusting where VMALLOC_* and FIXADDR_* are
defined.  This fixes the definition of the MEMMAP_* macros.

  CC      init/main.o
In file included from ./include/linux/mm.h:99,
                 from ./include/linux/ring_buffer.h:5,
                 from ./include/linux/trace_events.h:6,
                 from ./include/trace/syscall.h:7,
                 from ./include/linux/syscalls.h:85,
                 from init/main.c:21:
./arch/riscv/include/asm/pgtable.h: In function ‘pmd_page’:
./arch/riscv/include/asm/pgtable.h:95:24: error: ‘VMALLOC_START’ undeclared (first use in this function); did you mean ‘VMEMMAP_START’?
 #define VMEMMAP_START (VMALLOC_START - VMEMMAP_SIZE)
                        ^~~~~~~~~~~~~

Fixes: d95f1a54 ("RISC-V: Implement sparsemem")
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
[paul.walmsley@sifive.com: minor patch description fix]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/include/asm/pgtable.h

@@ -83,6 +83,18 @@ extern pgd_t swapper_pg_dir[];
 #define __S110	PAGE_SHARED_EXEC
 #define __S111	PAGE_SHARED_EXEC
 
+#define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
+#define VMALLOC_END      (PAGE_OFFSET - 1)
+#define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
+
+#define FIXADDR_TOP      VMALLOC_START
+#ifdef CONFIG_64BIT
+#define FIXADDR_SIZE     PMD_SIZE
+#else
+#define FIXADDR_SIZE     PGDIR_SIZE
+#endif
+#define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
+
 /*
  * Roughly size the vmemmap space to be large enough to fit enough
  * struct pages to map half the virtual address space. Then
@@ -429,18 +441,6 @@ static inline void pgtable_cache_init(void)
 	/* No page table caches to initialize */
 }
 
-#define VMALLOC_SIZE     (KERN_VIRT_SIZE >> 1)
-#define VMALLOC_END      (PAGE_OFFSET - 1)
-#define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
-
-#define FIXADDR_TOP      VMALLOC_START
-#ifdef CONFIG_64BIT
-#define FIXADDR_SIZE     PMD_SIZE
-#else
-#define FIXADDR_SIZE     PGDIR_SIZE
-#endif
-#define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
-
 /*
  * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32.
  * Note that PGDIR_SIZE must evenly divide TASK_SIZE.