cris: fix potential NULL-pointer dereference

Add missing check for memory allocation fail.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mikael Starvik <starvik@axis.com>
Acked-by: NJesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/cris/include/asm/pgalloc.h

@@ -32,6 +32,8 @@ static inline pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long addres
 {
 	struct page *pte;
 	pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
+	if (!pte)
+		return NULL;
 	pgtable_page_ctor(pte);
 	return pte;
 }