linux-imx

include/linux/blkdev.h: use NULL instead of zero

Quite useless but it shuts up some warnings.

Signed-off-by: Michele Curti <michele.curti@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>