CFT: lem(4), em(4) e1000 Ethernet TSO testing

Hi,

I have been working through various bugs and have come to a point
where TSO is working on systems I have available for testing.

This results in higher throughput on resource constrained systems, and
less CPU/power usage on unconstrained systems.

As of this mail, you will need to manually apply
https://reviews.freebsd.org/D41170 on top of main to use TSO6 on
em(4).

I plan to enable TSO by default for lem(4) and em(4) during the
FreeBSD 14 release cycle, so I would appreciate testing to address any
remaining issues.  Below, a list of chipsets that will be exempt due
to known issues.

lem(4) exclusions:
* <82544 (although it does seem ok to manually enable for emulations
in qemu, virtualbox, etc)
* 82547

em(4) exclusions.. These chips have a stability workaround for high
throughput with rapid link-flap applied that results in the TSO engine
not being able to run at line speed.  Thus, TSO would not be enabled
by default here:
* Intel(R) I219-LM and I219-V
* Intel(R) I219-LM and I219-V (2)
* Intel(R) I219-LM and I219-V (3)
* Intel(R) I219-LM and I219-V (4)
* Intel(R) I219-LM and I219-V (5)

Regards,
Kevin Bowling