brcm80211: fmac: remove oneline proto block functions

brcmf_os_proto_block and brcmf_os_proto_unblock are oneline
functions handling proto_block mutex. Place the mutex interface
call inline to increase readability.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>