drm/radeon/kms: fix tv dac conflict resolver

drm/radeon/kms: fix tv dac conflict resolver

commit 08d075116db3592db218bfe0f554cd93c9e12505 upstream.

On systems with the tv dac shared between DVI and TV,
we can only use the dac for one of the connectors.
However, when using a digital monitor on the DVI port,
you can use the dac for the TV connector just fine.
Check the use_digital status when resolving the conflict.

Fixes fdo bug 27649, possibly others.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>