net/bnxt: use first completion ring for fwd and async event

net/bnxt: use first completion ring for fwd and async event

In order to save completion resource, use the first completion ring from
PF or VF as the default completion ring for async event & HWRM forward
response handling. Add bnxt_hwrm_set_async_event_cr() to set
async_event_cr for either PF or VF.

Fixes: 7bc8e9a227cc ("net/bnxt: support async link notification")
Signed-off-by: Qingmin Liu <qingmin.liu@broadcom.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>