drm/i915: don't enable self-refresh on Ironlake

drm/i915: don't enable self-refresh on Ironlake

commit dd8849c8f59ec1cee4809a0c5e603e045abe860e upstream.

We don't know how to enable it safely, especially as outputs turn on and
off.  When disabling LP1 we also need to make sure LP2 and 3 are already
disabled.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29173
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29082
Reported-by: Chris Lord <chris@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>