[SCSI] zfcp: Prevent access on uninitialized memory.

Initialize allocated memory to zero to prevent access on error. This
prevents a possible error in the error handling path.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>