Revert "radeon, kdb, kms: Save and restore the LUT on atomic KMS enter/exit"

This reverts commit ff773714.

A generic solution is needed to save and retore the LUT information.

CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: dri-devel@lists.freedesktop.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>