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 r244280 (by pjd):
sbuf_trim() cannot be used on sbuf with drain function set.
This fixes panic when listing sysctls on INVARIANTS-enabled kernel while
having wbwd loaded.

This panic was not fatal, at worst one additional space was printed.

Also sbuf_trim() makes some sense even if drain function is set. The drain
function is called only when buffer is to be expanded. So we could still trim
existing buffer before drain is called. In this case it worked just fine - the
trailing space was correctly trimmed.

MFC r245297:

Add ID for Nuvoton WPCM450RA0BX found on Supermicro X9SCA-F motherboards.

While I'm there, also make this driver to attach to devices that have
an unknown device ID.

MFC r244787, 244796:

Add DEVICE_IDENTIFY method for wbwd(4), required on most of recent
Supermicro motherboards.

Tested on X8STi and X8DTH boards.

Sponsored by: iXsystems, Inc.

MFC r244781:

Use DEVMETHOD_END.

MFC r236246

Add device ids for the Winbond 83627DHG-P chip and set the registers to
trigger the keyboard reset line on timeout.

MFC r236245

Fix a typo in wbwd so that CRF5 is actually written to the data register
rather than the index register.

MFC r232614:

Provide wbwd(4), a driver for the watchdog timer found on various
Winbond Super I/O chips.

Provide wbwd(4), a driver for the watchdog timer found on various
Winbond Super I/O chips.

With minor efforts it should be possible the extend the driver to support
further chips/revisions available from Winbond. In the simplest case
only new IDs need to be added, while different chipsets might require
their own function to enter extended function mode, etc.

Sponsored by: Sandvine Incorporated ULC (in 2011)
Reviewed by: emaste, brueffer
MFC after: 2 weeks