ksm: remove redundant __GFP_ZERO from kcalloc

kcalloc returns zeroed memory.  There's no need to use this flag.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>