is_power_of_2: kernel/kfifo.c

Replace (n & (n-1)) with is_power_of_2()

Signed-off-by: vignesh babu <vignesh.babu@wipro.com>
Acked-by: Stelian Pop <stelian@popies.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>