alpha: 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: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Acked-by: Matt Turner <mattst88@gmail.com>
Cc: Phil Carmody <pc+lkml@asdf.org>
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Matt Turner <mattst88@gmail.com>

arch/alpha/kernel/sys_marvel.c

@@ -331,7 +331,7 @@ marvel_map_irq(const struct pci_dev *cdev, u8 slot, u8 pin)
 	pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &intline);
 	irq = intline;
 
-	msi_loc = pci_find_capability(dev, PCI_CAP_ID_MSI);
+	msi_loc = dev->msi_cap;
 	msg_ctl = 0;
 	if (msi_loc) 
 		pci_read_config_word(dev, msi_loc + PCI_MSI_FLAGS, &msg_ctl);