rt2x00: Centralize setting of extra TX headroom requested by rt2x00.

Set the value of extra_tx_headroom in a central place, rather than in each
of the drivers. This is preparatory for taking alignment space into account
in the TX headroom requested by rt2x00.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 1cbb7ac..4d841c0 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -588,6 +588,7 @@
 	const unsigned int eeprom_size;
 	const unsigned int rf_size;
 	const unsigned int tx_queues;
+	const unsigned int extra_tx_headroom;
 	const struct data_queue_desc *rx;
 	const struct data_queue_desc *tx;
 	const struct data_queue_desc *bcn;