PCI: remove useless pcix_set_mmrbc() dev->bus check

For a valid pci_dev, dev->bus != NULL always, so remove this
unnecessary test.

Found by Coverity (CID 101680).

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b9e93cf..7f1310e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3395,8 +3395,7 @@
 
 	o = (cmd & PCI_X_CMD_MAX_READ) >> 2;
 	if (o != v) {
-		if (v > o && dev->bus &&
-		   (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_MMRBC))
+		if (v > o && (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_MMRBC))
 			return -EIO;
 
 		cmd &= ~PCI_X_CMD_MAX_READ;