iwlegacy: fix command queue timeout

iwlegacy version of fix:

commit 282cdb32
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Mon Sep 12 12:09:10 2011 -0700

    iwlagn: fix command queue timeout

    If the command queue is constantly busy,
    which can happen in P2P, the hangcheck
    timer will frequently find a command in
    it and will eventually reset the device
    because nothing sets the timestamp for
    this queue when commands are processed.

    Fix this by setting the timestamp when
    a command completes.

iwlegacy does not support P2P, but this patch fix possible
unneeded hardware resets, hence is needed.

Cc: stable@kernel.org  # 2.6.39+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>