Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Remove trailing whitespace per mdoc lint warning

Disussed with: gavin
No objection from: doc
Approved by: joel
MFC after: 3 days

Don't mention 'device acpi' or loading ACPI as a kernel module since the
latter is not supported. This is also more consistent with manpages for
other vendor-specific drivers such as acpi_ibm(4) and acpi_sony(4).

Import the acpi_aibs(4) driver written by Constantine A. Murenin.
It has more features than acpi_aiboost(4) and it will eventually replace
acpi_aiboost(4).

Submitted by: Constantine A. Murenin <cnst at FreeBSD.org>
Reviewed by: freebsd-acpi, imp
MFC after: 1 month