mac80211: fix remain_off_channel regression

The offchannel code is currently broken - we should
remain_off_channel if the work was started, and
the work's channel and channel_type are the same
as local->tmp_channel and local->tmp_channel_type.

However, if wk->chan_type and local->tmp_channel_type
coexist (e.g. have the same channel type), we won't
remain_off_channel.

This behavior was introduced by commit da2fd1f0
("mac80211: Allow work items to use existing
channel type.")

Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Cc: stable@kernel.org # 2.6.39+
Signed-off-by: John W. Linville <linville@tuxdriver.com>