net/bnxt: cleanup NQ doorbell

net/bnxt: cleanup NQ doorbell

Simplify nq doorbell handling code by removing redundant db
parameter and consolidating NQ doorbell macro into the inline
function that uses it.

Add "enable interrupt" variant of nq write. This will be used
in a subsequent commit.

When initializing nq doorbell, don't assume that only the
"disable interrupt" form will be used.

Fixes: f8168ca0e690 ("net/bnxt: support thor controller")

Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>