PCI: Make bus_attr_resource_alignment static

The symbol bus_attr_resource_alignment is not exported or declared
elsewhere, so make it static to fix the following warning:

  drivers/pci/pci.c:4900:1: warning: symbol 'bus_attr_resource_alignment' was not declared. Should it be static?
Signed-off-by: NBen Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -4897,7 +4897,7 @@ static ssize_t pci_resource_alignment_store(struct bus_type *bus,
 	return pci_set_resource_alignment_param(buf, count);
 }
 
-BUS_ATTR(resource_alignment, 0644, pci_resource_alignment_show,
+static BUS_ATTR(resource_alignment, 0644, pci_resource_alignment_show,
 					pci_resource_alignment_store);
 
 static int __init pci_resource_alignment_sysfs_init(void)