tg3: clean up unnecessary MSI/MSI-X capability find

PCI core will initialize device MSI/MSI-X capability in
pci_msi_init_pci_dev(). So device driver should use
pci_dev->msi_cap/msix_cap to determine whether the device
support MSI/MSI-X instead of using
pci_find_capability(pci_dev, PCI_CAP_ID_MSI/MSIX).
Access to PCIe device config space again will consume more time.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Cc: Nithin Nayak Sujir <nsujir@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -15967,7 +15967,7 @@ static int tg3_get_invariants(struct tg3 *tp, const struct pci_device_id *ent)
 	 */
 	if (tg3_flag(tp, 5780_CLASS)) {
 		tg3_flag_set(tp, 40BIT_DMA_BUG);
-		tp->msi_cap = pci_find_capability(tp->pdev, PCI_CAP_ID_MSI);
+		tp->msi_cap = tp->pdev->msi_cap;
 	} else {
 		struct pci_dev *bridge = NULL;