PCI: fix new kernel-doc warning

Fix pci.c kernel-doc warnings:

Warning(drivers/pci/pci.c:3292): No description found for parameter 'flags'
Warning(drivers/pci/pci.c:3292): Excess function parameter 'change_bridge_flags' description in 'pci_set_vga_state'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>