staging: vt6655: change tx wake queue

Wake queue in the dwIsr loop of device_intr instead of device_tx_srv.

This fixes an issue when ISR_TXDMA0 or ISR_AC0DMA does not occur
device_tx_srv is not called and the queue gets stuck in stopped
condition.

On test if the queue is stuck another MACvTransmitAC0 or MACvTransmit0
in vnt_tx_packet will clear it.

Check on vif that both buffers are available and the queue is stopped.

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