Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

- There's no need to overwrite the default device method with the default
one. Interestingly, these are actually the default for quite some time
(bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
since r52045) but even recently added device drivers do this unnecessarily.
Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
Discussed with: jhb
- Also while at it, use __FBSDID.

Merge r207585 from cas(4):
- Don't probe for PHYs if we already know to use a SERDES. Unlike as with
cas(4) this only serves to speed up the the device attach though and can
only be determined via the OFW device tree but not from the VPD.
- Don't touch the MIF when using a SERDES.
- Add some missing bus space barriers, mainly in the PCS code path.

- Initialize the ifnet structure, especially if_dname, before probing
the PHYs as some PHY drivers use it (but probably shouldn't). How
gem(4) has worked with brgphy(4) on powerpc without this so far is
unclear to me.
- Introduce a dying flag which is set during detach and checked in
gem_ioctl() in order to prevent active BPF listeners to clear
promiscuous mode which may lead to the tick callout being restarted
which will trigger a panic once it's actually gone.
- In gem_stop() reset rather than just disable the transmitter and
receiver in order to ensure we're not unloading DMA maps still in
use by the hardware. [1]
- The blanking time is specified in PCI clocks so we should use twice
the value when operating at 66MHz.
- Spell some 2 as ETHER_ALIGN and a 19 as GEM_STATUS_TX_COMPLETION_SHFT
to make the actual intentions clear.
- As we don't unload the peak attempts counter ignore its overflow
interrupts.
- Remove a stale setting of a variable to GEM_TD_INTERRUPT_ME which
isn't used afterwards.
- For optimum performance increment the TX kick register in multiples
of 4 if possible as suggested by the documentation.
- Partially revert r164931; drivers should only clear the watchdog
timer if all outstanding TX descriptors are done.
- Fix some debugging strings.
- Add a missing BUS_DMASYNC_POSTWRITE in gem_rint().
- As the error paths in the interrupt handler are generally unlikely
predict them as false.
- Add support for the SBus version of the GEM controller. [2]
- Add some lock assertions.
- Improve some comments.
- Fix some more or less cosmetic issues in the code of the PCI front-end.
- Change some softc members to be unsigned where more appropriate and
remove unused ones.

Approved by: re (kib)
Obtained from: NetBSD (partially) [2], OpenBSD [1]
MFC after: 2 weeks