[SCSI] zfcp: Replace kmalloc/memset with kzalloc

Memory allocated with kmalloc is always initialzed to 0 with memset.
Replace the two calls with kzalloc, that already does both steps.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>