net: chelsio: cxgb3: check the return value of pci_find_capability()

The function pci_find_capability() in t3_prep_adapter() can fail, so its
return value should be checked.

Fixes: 4d22de3e ("Add support for the latest 1G/10G Chelsio adapter, T3")
Reported-by: NTOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: NJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb3/t3_hw.c

@@ -3613,6 +3613,8 @@ int t3_prep_adapter(struct adapter *adapter, const struct adapter_info *ai,
 	    MAC_STATS_ACCUM_SECS : (MAC_STATS_ACCUM_SECS * 10);
 	adapter->params.pci.vpd_cap_addr =
 	    pci_find_capability(adapter->pdev, PCI_CAP_ID_VPD);
+	if (!adapter->params.pci.vpd_cap_addr)
+		return -ENODEV;
 	ret = get_vpd_params(adapter, &adapter->params.vpd);
 	if (ret < 0)
 		return ret;