bnxt_en: Store the maximum NQs available on the PF.

The PF has a pool of NQs and MSIX vectors assigned to it based on
NVRAM configurations.  The number of usable MSIX vectors on the PF
is the minimum of the NQs and MSIX vectors.  Any excess NQs without
associated MSIX may be used for the VFs, so we need to store this
max_nqs value.  max_nqs minus the NQs used by the PF will be the
available NQs for the VFs.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>