rt2x00: Fix queue_idx initialization

For TX rings the queue_idx should start at
IEEE80211_TX_QUEUE_DATA0 and for each followup
ring this index needs to be increased.

For the RX ring the queue_idx should be set
to 0. We don't need to initialize the tx_params.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>