linux-yocto/4.8: sync preempt-rt with upstream project

linux-yocto/4.8: sync preempt-rt with upstream project

The initial 4.8 -rt feature was directly from Paul Gortmaker, and
now the 'upstream' -rt has done a release on the same kernel
version.

Paul has sync'd the initial effort with the upstream work, and we
now have a consolidated standard/preempt-rt/*

Along with the rsync'd content, Paul has fixed -rt boot on 32 bit
x86.

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>