commit 091264f0 upstream.

Can happen when there is no DP panel attached, confusing
users.  Make it debug only.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>