net/bnxt: use dedicated CPR for async events

net/bnxt: use dedicated CPR for async events

This commit enables the creation of a dedicated completion
ring for asynchronous event handling instead of handling these
events on a receive completion ring.

For the stingray platform and other platforms needing tighter
control of resource utilization, we retain the ability to
process async events on a receive completion ring.

For Thor-based adapters, we use a dedicated NQ (notification
queue) ring for async events (async events can't currently
be received on a completion ring due to a firmware limitation).

Rename "def_cp_ring" to "async_cp_ring" to better reflect its
purpose (async event notifications) and to avoid confusion with
VNIC default receive completion rings.

Allow rxq 0 to be stopped when not being used for async events.

Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>