bcma: add constants for PCI and use them

There are many magic numbers used in the PCIe code. Replace them with
some constants from the Broadcom SDK and also use them in the pcie host
controller.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>