scsi: be2iscsi: allocate enough memory in beiscsi_boot_get_sinfo()

We accidentally allocate sizeof(u32) instead of sizeof(struct
be_cmd_get_session_resp).

Fixes: 50a4b824 ("scsi: be2iscsi: Fix to make boot discovery non-blocking")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed by: Jitendra Bhivare <jitendra.bhivare@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>