cxgb4: Check for kvzalloc allocation failure

t4_prep_fw doesn't check for card_fw pointer before store the read data,
which could lead to a NULL pointer dereference if kvzalloc failed.
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -4140,6 +4140,10 @@ static int adap_init0(struct adapter *adap)
 		 * card
 		 */
 		card_fw = kvzalloc(sizeof(*card_fw), GFP_KERNEL);
+		if (!card_fw) {
+			ret = -ENOMEM;
+			goto bye;
+		}
 
 		/* Get FW from from /lib/firmware/ */
 		ret = request_firmware(&fw, fw_info->fw_mod_name,