powerpc/mm: Fix build error with hugetlfs disabled

arch/powerpc/mm/slice.c:704:5: error: expected identifier or ‘(’ before numeric constant
int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
^
make[1]: *** [arch/powerpc/mm/slice.o] Error 1
make: *** [arch/powerpc/mm/slice.o] Error 2

This got introduced via 1217d34b531c76362217057ca70a8ce8950574e0
"powerpc: Ensure global functions include their prototype". We
started including linux/hugetlb.h with that patch and now we have

#define is_hugepage_only_range(mm, addr, len) 0

with hugetlbfs disabled.

Fixes: 1217d34b531c ("powerpc: Ensure global functions include their prototype")
Signed-off-by: Aneesh Kumar K.V <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/mm/slice.c

···
 	slice_convert(mm, mask, psize);
 }
 
+#ifdef CONFIG_HUGETLB_PAGE
 /*
  * is_hugepage_only_range() is used by generic code to verify whether
  * a normal mmap mapping (non hugetlbfs) is valid on a given area.
···
 #endif
 	return !slice_check_fit(mask, available);
 }
-
+#endif