Use kzalloc rather than kmalloc followed by memset with 0.

Generated by: scripts/coccinelle/api/alloc/kzalloc-simple.cocci
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>