brcmfmac: remove pcie gen1 support

The PCIE bus driver supports older gen1 (v1) chips, but there is no
actual device which is using this older pcie core which is supported
by brcmfmac. Remove all gen1 related code.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>