qlnx: Report SR-IOV VF status

[kbowling]

Summary

Retain the effective MAC and allocated receive-queue count for each VF
and expose them through the PF ifnet.  Sum queues across all hardware
functions rather than reporting only the first one.

Publish and snapshot the VF cache under the existing hardware lock so
status queries cannot race IOV configuration or teardown.

Initialize the cache, release it on failed initialization, and reject
an out-of-range VF index instead of continuing into the array.

[kbowling]

This is a basic implementation, someone more familiar with the driver may look at the nvlist schema and https://reviews.freebsd.org/D58739 which demonstrates driver extensions.