UPSTREAM: include/linux/mm.h: add PAGE_ALIGNED() helper

To test whether an address is aligned to PAGE_SIZE.

Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 0fa73b86ef0797ca4fde5334117ca0b330f08030)

Bug: 36007193
Change-Id: I7e912bb0dbd8c9737fb13c5b48acb54ee39dd5fc