staging: brcm80211: replace semaphore by wait_queue for sysioc thread

The sysioc thread was triggered using a semaphore. Now it waits for
a wake_up() on its wait queue and the semaphore has been removed as
the semaphore serves another purpose. This removes a checkpatch
warning for dhd_linux.c.

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