mm/util: use offset_in_page macro

linux/mm.h provides offset_in_page() macro.  Let's use already predefined
macro instead of (addr & ~PAGE_MASK).

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/util.c b/mm/util.c
index 68ff8a5..9af1c12 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -309,7 +309,7 @@
 {
 	if (unlikely(offset + PAGE_ALIGN(len) < offset))
 		return -EINVAL;
-	if (unlikely(offset & ~PAGE_MASK))
+	if (unlikely(offset_in_page(offset)))
 		return -EINVAL;
 
 	return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);