drm/radeon: program DCE2 audio dto just like DCE3

commit 55d4e020fb8ddd3896a8cd3351028f5c3a2c4bd3 upstream.

Seems to work like the DCE3 version despite what
the register spec says.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=71975



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