Merge branch 'topic/uaccess-ppc' into next

Merge our uaccess-ppc topic branch. It is based on the uaccess topic
branch that we're sharing with Viro.

This includes the addition of user_[read|write]_access_begin(), as
well as some powerpc specific changes to our uaccess routines that
would conflict badly if merged separately.

diff --cc arch/powerpc/include/asm/uaccess.h
Simple merge