bnxt_en: Fix NQ/CP rings accounting on the new 57500 chips.

The new 57500 chips have introduced the NQ structure in addition to
the existing CP rings in all chips.  We need to introduce a new
bnxt_nq_rings_in_use().  On legacy chips, the 2 functions are the
same and one will just call the other.  On the new chips, they
refer to the 2 separate ring structures.  The new function is now
called to determine the resource (NQ or CP rings) associated with
MSIX that are in use.

On 57500 chips, the RDMA driver does not use the CP rings so
we don't need to do the subtraction adjustment.

Fixes: 41e8d798 ("bnxt_en: Modify the ring reservation functions for 57500 series chips.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>