[SCSI] be2iscsi: fix lock imbalance

Stanse found that one error path in mgmt_invalidate_icds omits to unlock
ctrl->mbox_lock. Fix that.

Added in 756d29c (Enable async mode for mcc rings)
where the spinlock was moved.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Jayamohan Kallickal <jayamohank@serverengines.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/be2iscsi/be_mgmt.c

@@ -169,6 +169,7 @@ unsigned char mgmt_invalidate_icds(struct beiscsi_hba *phba,
 		SE_DEBUG(DBG_LVL_1,
 			 "Failed to allocate memory for"
 			 "mgmt_invalidate_icds \n");
+		spin_unlock(&ctrl->mbox_lock);
 		return -1;
 	}
 	nonemb_cmd.size = sizeof(struct invalidate_commands_params_in);