can: c_can_pci: enable PCI bus master only for MSI

Coverity complains that c_can_pci_probe() calls pci_enable_msi() without
checking the result:

CID 712278 (#1 of 1): Unchecked return value (CHECKED_RETURN) 3. check_return:
Calling pci_enable_msi_block without checking return value (as is done
elsewhere 88 out of 105 times).
 88        pci_enable_msi(pdev);

This is CID 712278.
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Reported-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/c_can/c_can_pci.c

@@ -84,8 +84,11 @@ static int c_can_pci_probe(struct pci_dev *pdev,
 		goto out_disable_device;
 	}
 
+	ret = pci_enable_msi(pdev);
+	if (!ret) {
+		dev_info(&pdev->dev, "MSI enabled\n");
 		pci_set_master(pdev);
-	pci_enable_msi(pdev);
+	}
 
 	addr = pci_iomap(pdev, 0, pci_resource_len(pdev, 0));
 	if (!addr) {