Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC ixgbe driver revisions 248901, 250108, and 251964

Add quad port probe support, this gives the admin proper information about the slot
(which should be a PCIE Gen 3 slot for this adapter) by looking back thru the PCI
parent devices to the slot device.

The fix above also corrects the bandwidth display to GT/s rather than the
incorrect Gb/s

Next, allow the use of ALTQ if you select the compile option IXGBE_LEGACY_TX.

Allow the use of 'unsupported' optic modules by a compile option as well.

Add a phy reset capability into the stop code, this is so a static configured
driver will still behave properly when taken down (not being able to unload it).

This revision synchronizes the shared code with Intel internal current code,
and note that it now includes DCB supporting code, this was necessitated by
some internal changes with the code, but it also will provide the opportunity
to develop this feature in the core driver down the road.

I have edited the README to get rid of some of the worse anachronisms in it
as well, its by no means as robust as I might wish at this point however.

Oh, I also have included some conditional stuff in the code so it will be
compatible in both the 9.X and 10 environments.

Performance has been a focus in recent changes and I believe this revision
driver will perform very well in most workloads.

MFC after: 2 weeks