staging: brcm80211: rename active_queue identifier

staging: brcm80211: rename active_queue identifier

The queue for pending transmit packets is called active_queue, but
the driver is only using one single queue. Therefor a more appro-
priate name has been given, ie. pkt_queue.

Cc: devel@linuxdriverproject.org
Cc: linux-wireless@vger.kernel.org
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Henry Ptasinski <henryp@broadcom.com>
Cc: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>