staging: vt6656: lock changes: vDMA0_tx_80211

vDMA0_tx_80211 is atomically called.

RFbSetPower can not be called atomically.

If wCurrentRate is different to pDevice->wCurrentRate call
bScheduleCommand WLAN_CMD_SETPOWER.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>