iwlwifi: do not set tx power when channel is changing

iwlwifi: do not set tx power when channel is changing

BugLink: http://bugs.launchpad.net/bugs/775809

commit f844a709a7d8f8be61a571afc31dfaca9e779621 upstream.

Mac80211 can request for tx power and channel change in one ->config
call. If that happens, *_send_tx_power functions will try to setup tx
power for old channel, what can be not correct because we already change
the band. I.e  error  "Failed to get channel info for channel 140 [0]",
can be printed frequently when operating in software scanning mode.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>