PCI: add stub for pci_set_consistent_dma_mask()

When CONFIG_PCI=n, there is no stub for pci_set_consistent_dma_mask(),
so add one like other similar stubs.  Otherwise there can be build errors,
as here:

linux-next-20080630/drivers/ssb/main.c:1175: error: implicit declaration of
function 'pci_set_consistent_dma_mask'

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