PCI: remove excess kernel-doc notation

Fix pci/rom.c kernel-doc function notation:

Warning(drivers/pci/rom.c:110): Excess function parameter or struct member 'return' description in 'pci_map_rom'
Warning(drivers/pci/rom.c:177): Excess function parameter or struct member 'return' description in 'pci_map_rom_copy'

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