staging: brcm80211: use wait queues instead of semaphores in wl_cfg80211.c

In wl_cfg80211.c two semaphores were used to trigger a task to process
an event. The wait queues are better suited for that purpose. This also
removes checkpatch warning on sema_init() calls in this source file.

Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>