drm: Fix DRM_FORCE_ON_DIGITAL use

A connector may be forced on from the command line via video=
command line setting. The digital output of dual-mode connectors
can also be specifically selected and forced on; eg., 'video=DVI-I-2:D'.
However, in this case, the connector->status will be mistakenly set to
connector_status_disconnected, and the connector will not be mode set.

Fix the connector->status when connector->force is DRM_FORCE_ON_DIGITAL.

Note that this seems to have been broken ever since the introduction
of the connector forcing support in

commit d50ba256
Author: Dave Airlie <airlied@linux.ie>
Date:   Wed Sep 23 14:44:08 2009 +1000

    drm/kms: start adding command line interface using fb.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
[danvet: Add note about that this never worked.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_probe_helper.c

@@ -118,7 +118,8 @@ static int drm_helper_probe_single_connector_modes_merge_bits(struct drm_connect
 		mode->status = MODE_UNVERIFIED;
 
 	if (connector->force) {
-		if (connector->force == DRM_FORCE_ON)
+		if (connector->force == DRM_FORCE_ON ||
+		    connector->force == DRM_FORCE_ON_DIGITAL)
 			connector->status = connector_status_connected;
 		else
 			connector->status = connector_status_disconnected;