drm/radeon: avoid bouncing connector status btw disconnected & unknown

Since force handling rework of d0d0a225
we could end up bouncing connector status btw disconnected and unknown.
When connector status change a call to output_poll_changed happen which
in turn ask again for detect but with force set.

So set the load detect flags whenever we report the connector as
connected or unknown this avoid bouncing btw disconnected and unknown.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>