rt2x00: Implement tx power temperature compensation

rt2800 devices should adjust their tx power in accordance with the
eeproms temperature calibration values. Add a new driver callback
gain_calibration that is called every 4 seconds.

The rt2800 gain calibration routine simply runs the tx power
configuration that takes care of calculating the temperature
compensation delta.

We don't need to synchronize the calls to rt2800_config_txpower
as they should all happen from mac80211's single threaded workqueue.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2800pci.c b/drivers/net/wireless/rt2x00/rt2800pci.c
index d305514..adc3534 100644
--- a/drivers/net/wireless/rt2x00/rt2800pci.c
+++ b/drivers/net/wireless/rt2x00/rt2800pci.c
@@ -1053,6 +1053,7 @@
 	.link_stats		= rt2800_link_stats,
 	.reset_tuner		= rt2800_reset_tuner,
 	.link_tuner		= rt2800_link_tuner,
+	.gain_calibration	= rt2800_gain_calibration,
 	.start_queue		= rt2800pci_start_queue,
 	.kick_queue		= rt2800pci_kick_queue,
 	.stop_queue		= rt2800pci_stop_queue,