staging: brcm80211: remove macro FOREACH_AS_STA

The macro definition FOREACH_AS_STA does an assignment inside the
if condition, which is considered a checkpatch error. It has been
removed.

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