net/cxgb4: Check the return from t4_query_params properly

Positive return values are also failures that don't set val,
although this probably can't happen. Fixes gcc 10 warning:

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c: In function ‘t4_phy_fw_ver’:
drivers/net/ethernet/chelsio/cxgb4/t4_hw.c:3747:14: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
 3747 |  *phy_fw_ver = val;

Fixes: 01b69614 ("cxgb4: Add PHY firmware support for T420-BT cards")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -3742,7 +3742,7 @@ int t4_phy_fw_ver(struct adapter *adap, int *phy_fw_ver)
 		 FW_PARAMS_PARAM_Z_V(FW_PARAMS_PARAM_DEV_PHYFW_VERSION));
 	ret = t4_query_params(adap, adap->mbox, adap->pf, 0, 1,
 			      &param, &val);
-	if (ret < 0)
+	if (ret)
 		return ret;
 	*phy_fw_ver = val;
 	return 0;