brcmsmac: remove PCIe functions needed for PCIe core rev <= 10

The devices I know of are not using a PCIe core with rev <= 10. The
BCM4718 uses a PCIe core with revision 14 and the BCM43224 uses a PCIe
core with revision 15. This patch removes support for old PCIe core
versions, which are not found on devices supported by brcmsmac.

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