brcmfmac: Add module parameter to disable features.

For debugging purpose it is very handy to be able to disable
features. It has happened a few times that new features turned
out not always being properly detected for all devices/firmwares.
Making it possible to disable the feature with a module parameter
will make testing/debugging easier.

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>