userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --cc init/Kconfig
Simple merge

diff --cc mm/mempolicy.c
Simple merge

diff --cc mm/migrate.c
Simple merge