drm/radeon/kms: rework modeset sequence for DCE41 and DCE5

commit 3a47824d upstream.

dig transmitter control table only has ENABLE/DISABLE actions
on DCE4.1/DCE5.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=44955



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>