mm: move the backup x_devmap() functions to asm-generic/pgtable.h

The asm-generic/pgtable.h include file appears to be the correct place for
the backup x_devmap() inline functions.  Moving them here is also
necessary if we want to include x_devmap() in the [pmd|pud]_unstable
functions.  So move the x_devmap() functions to asm-generic/pgtable.h

Link: http://lkml.kernel.org/r/20191115115808.21181-1-thomas_os@shipmail.orgSigned-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-generic/pgtable.h

@@ -914,6 +914,21 @@ static inline int pud_write(pud_t pud)
 }
 #endif /* pud_write */
 
+#if !defined(CONFIG_ARCH_HAS_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
+static inline int pmd_devmap(pmd_t pmd)
+{
+	return 0;
+}
+static inline int pud_devmap(pud_t pud)
+{
+	return 0;
+}
+static inline int pgd_devmap(pgd_t pgd)
+{
+	return 0;
+}
+#endif
+
 #if !defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
 	(defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
 	 !defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD))

include/linux/mm.h

@@ -564,21 +564,6 @@ int vma_is_stack_for_current(struct vm_area_struct *vma);
 struct mmu_gather;
 struct inode;
 
-#if !defined(CONFIG_ARCH_HAS_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
-static inline int pmd_devmap(pmd_t pmd)
-{
-	return 0;
-}
-static inline int pud_devmap(pud_t pud)
-{
-	return 0;
-}
-static inline int pgd_devmap(pgd_t pgd)
-{
-	return 0;
-}
-#endif
-
 /*
  * FIXME: take this include out, include page-flags.h in
  * files which need it (119 of them)