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

Match the right backlight driver.

Some ATI-based PowerBooks use the string 'mnca' in the backlight controller
device tree entry, so account for this and don't use nVidia when it's not an
nVidia device.

MFC after: 3 weeks

Don't set the write bit if we're just reading.

Also fix a couple typos.

MFC after: 3 weeks

Clear the backlight level when it's turned off. Also, reduce the delay times to
less conservative values, also found in the radeonkms driver.

MFC after: 2 weeks
X-MFC-with: r264205

Fix the ATI backlight driver off/on handling. Now this driver works correctly
with the ATI Radeon 9700 in the PowerBook G4 1.67GHz.

Code shamelessly taken in spirit from the radeonkms driver, which I hope will
make this driver redundant in the future.

MFC after: 2 weeks

Add suspend/resume handlers for ATI backlight ppc driver.

With this, also shut shut off the display (DPMS-style) and disable the clocking
when the backlight level is set to 0. This is taken from the radeonkms driver
(radeon_legacy_encoders.c) which doesn't yet support PowerPC, and won't for a
while, as it's missing full AGP support.

Only add the backlight device if it actually exists in OF.

MFC after: 1 week

phandle_t is unsigned, and OF_finddevice() returns (phandle_t)(-1) on
failure, so check for that instead of 0.

While here, provide a better description for ATI backlight driver.

Reported by: jchandra@
MFC after: 3 days

Add backlight control to ATI-graphics PowerBooks and iBooks.

Approved by: nwhitehorn (mentor)
MFC after: 1 week