This macro is already defined in uapi header.  Also use this macro where
possible.

Link: http://lkml.kernel.org/r/148577166656.9801.10322423666945951186.stgit@pluto.themaw.netSigned-off-by: NTomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: NIan Kent <raven@themaw.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>