PCI: Use pci_is_pcie() to simplify code

Use pci_is_pcie() instead of pci_find_capability() to simplify code.
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

@@ -641,8 +641,7 @@ static void pci_set_bus_speed(struct pci_bus *bus)
 		return;
 	}
 
-	pos = pci_find_capability(bridge, PCI_CAP_ID_EXP);
-	if (pos) {
+	if (pci_is_pcie(bridge)) {
 		u32 linkcap;
 		u16 linksta;