drm/i915/ddi: warn instead of oops on invalid ddi encoder type

It's more useful to limp on than bring the kernel down. Hitting this is
a more likely event with BXT DSI, although care should be taken not to
call the function for DSI.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -322,8 +322,7 @@ static void ddi_get_encoder_port(struct intel_encoder *intel_encoder,
 		*dig_port = NULL;
 		*port = PORT_E;
 	} else {
-		DRM_ERROR("Invalid DDI encoder type %d\n", type);
-		BUG();
+		WARN(1, "Invalid DDI encoder type %d\n", type);
 	}
 }