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 r244123 Add CTLFLAG_RWTUN define
MFC r247367 Fix non-recusive mutex MFI I/O lock
MFC r247369 Fix a large amount of bugs in MFI that cause panics

Approved by: pjd (mentor)

MFC r249257:
Add support for getting and setting BBU properties related to battery
relearning. Specifically, add subcommands to mfiutil(8) which allow the
user to set the BBU and autolearn modes when the firmware supports it,
and add a subcommand which kicks off a battery relearn.

MFC r249258:
Switch to a 2-clause license.

MFC r235014: Rebuild fix and LBA calculation fix for ThunderBolt
based cards.

MFC r235016: Some style improvements.

MFC r235040: Fix the returns in mfi_tbolt_sync_map_info that I added.

PR: 167226

MFC r233711:
Major update to driver to support for Drake Skinny and ThunderBolt cards.

MFC r233768:
Change typedef atomic_t to struct mfi_atomic to avoid name space
collision and some couple more style changes.

MFC r233805:
Move struct megasas_sge from mfi_ioctl.h to mfivar.h so we can
remove including machine/bus.h. Add some more mfi_ prefixes to
avoid name space pollution.

MFC r233877:
- Do not include machine/atomic.h. It is no longer necessary since r233768.
- Remove bogus "atomic" macros and a read-only variable from softc.

MFC 227577: The sys/sysctl.h header is needed when MFI_DEBUG is defined.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

- Add a command validator for use in debugging.
- Fix the locking protocol to eliminate races between normal I/O and AENs.
- Various small improvements and usability tweaks.

Sponsored by: IronPort
Portions Submitted by: Doug Ambrisko

Fix a bad #include statment

Add a command debugging module and a periodic watchdog timer.

Sponsored by: IronPort