brcmfmac: Make FWS queueing configurable.

FWS is always queuing frames and using a worker for de-queueing,
this is not always efficient for all bus layer. For example SDIO
has an internal queue and worker making the queueing of FWS
unnecessary. Make it possible to bypass the worker if fws mode
is none using a bus interface configuration. For USB bus layer
this configuration is set true to have fws provide queueing
regardless the fws mode.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Daniel (Deognyoun) Kim <dekim@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>