Chelsio T6 NIC can support up to 8 priority channels to manage
congestion. So, increase to 8 congestion channels for T6. Also,
add Rxq state to avoid unnecessarily ringing doorbell and polling
the hardware for more traffic when the Rxq is stopped.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>