bcma: add an extra pcie core struct

The BCM4706 has two PCIe host controller on the bcma bus. For PCIe
client mode it is assumed that there is only one PCIe controller so the
PCIe driver, like b43 and brcmsmac are accessing the first PCIe
controller when they want to issue a operation on the host controller.

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