drm/radeon/kms: reset ddc_bus in object header parsing

Some LVDS connectors don't have a ddc bus, so reset the
ddc bus to invalid before parsing the next connector
to avoid using stale ddc bus data.  Should fix
fdo bug 28164.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -530,6 +530,8 @@ bool radeon_get_atom_connector_info_from_object_table(struct drm_device *dev)
 			}
 
 			/* look up gpio for ddc, hpd */
+			ddc_bus.valid = false;
+			hpd.hpd = RADEON_HPD_NONE;
 			if ((le16_to_cpu(path->usDeviceTag) &
 			     (ATOM_DEVICE_TV_SUPPORT | ATOM_DEVICE_CV_SUPPORT)) == 0) {
 				for (j = 0; j < con_obj->ucNumberOfObjects; j++) {
@@ -585,9 +587,6 @@ bool radeon_get_atom_connector_info_from_object_table(struct drm_device *dev)
 						break;
 					}
 				}
-			} else {
-				hpd.hpd = RADEON_HPD_NONE;
-				ddc_bus.valid = false;
 			}
 
 			/* needed for aux chan transactions */