drm/radeon: fix audio dto programming on DCE4+

commit 7d61d835824f73dc4097b51f800382467c8049c5 upstream.

We need to set the dto source before setting the
dividers otherwise we may get stability problems
with the dto leading to audio playback problems.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>