staging: vt6656: vnt_rf_set_txpower use power for priv->byCurPwr

The byCurPwr value can change state while in another thread,.

Change to local variable power which is the last set value.

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