s390/mm: fix -Wunused-but-set-variable warnings

Convert two functions to static inline to get ride of W=1 GCC warnings
like,

mm/gup.c: In function 'gup_pte_range':
mm/gup.c:1816:16: warning: variable 'ptem' set but not used
[-Wunused-but-set-variable]
  pte_t *ptep, *ptem;
                ^~~~

mm/mmap.c: In function 'acct_stack_growth':
mm/mmap.c:2322:16: warning: variable 'new_start' set but not used
[-Wunused-but-set-variable]
  unsigned long new_start;
                ^~~~~~~~~
Signed-off-by: Qian Cai <cai@lca.pw>
Link: https://lore.kernel.org/lkml/1570138596-11913-1-git-send-email-cai@lca.pw/Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/hugetlb.h

@@ -12,8 +12,6 @@
 #include <asm/page.h>
 #include <asm/pgtable.h>
 
-
-#define is_hugepage_only_range(mm, addr, len)	0
 #define hugetlb_free_pgd_range			free_pgd_range
 #define hugepages_supported()			(MACHINE_HAS_EDAT1)
 
@@ -23,6 +21,13 @@ pte_t huge_ptep_get(pte_t *ptep);
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 			      unsigned long addr, pte_t *ptep);
 
+static inline bool is_hugepage_only_range(struct mm_struct *mm,
+					  unsigned long addr,
+					  unsigned long len)
+{
+	return false;
+}
+
 /*
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.

arch/s390/include/asm/pgtable.h

@@ -1269,7 +1269,8 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address)
 
 #define pte_offset_kernel(pmd, address) pte_offset(pmd, address)
 #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
-#define pte_unmap(pte) do { } while (0)
+
+static inline void pte_unmap(pte_t *pte) { }
 
 static inline bool gup_fast_permitted(unsigned long start, unsigned long end)
 {