brcmsmac: remove PCIE() macro

Instead of checking if there is a PCIe core on the bus, better check if
hosttype is PCIe.

In the original submission to staging PCIE() checked, if the bustype is
PCI and the buscore is a PCIe core. Now we assume that all cores bcma
supports are PCIe based, so we just have to check if the bustype is PCI.

The old code bcmsmac currently uses searches for a PCIe core on the bus
and if there is one assumes that this is the buscore, which is wrong.
Some SoCs have a PCIe core operating in host mode and this is not the
bus core. The old code also caused a null pointer in
ai_get_buscoretype() and ai_get_buscorerev() if buscore was not set
because there was no PCIe core on the bus.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>