Initializing sc->nqsets here means it may not have a good value until a
port (any port) of the adapter is brought up administratively. This may
work for netdump. If not then setup sc->nqsets in t3_sge_prep instead,
which runs very early.

I tried the latest diff and ran into an assertion on VLAN creation:

I decided to grab the PCP from the ifvlan (like VLAN_TAG does). I believe ifconfig ... vlanpcp <foo> updates this field.
ifconfig ... pcp <foo> updates the if_pcp field but I don't see any code that attempts to keep the ifvlan's pcp
and the ifnet's pcp in sync when the ifnet is a vlan ifnet.

This is modeled after VLAN_TAG (which is mislabeled and just returns the
vid instead of the entire tag). I'm ok with changing the behavior of
VLAN_TAG to return the full tag including pcp but I went with a separate
VLAN_PCP to avoid surprising existing users of VLAN_TAG.