radeon/kms: force rn50 chip to always report connected on analog output

Those rn50 chip are often connected to console remoting hw and load
detection often fails with those. Just don't try to load detect and
report connect.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org