drivers/rc/crsf_rc: update standalone driver for CRSF and direct support for lq/rssi (#20084)

Co-authored-by: Chris Seto <chris1seto@gmail.com>

src/modules/mavlink/mavlink_receiver.cpp

@@ -2126,6 +2126,9 @@ MavlinkReceiver::handle_message_rc_channels_override(mavlink_message_t *msg)
 		}
 	}
 
+	rc.link_quality = -1;
+	rc.rssi_dbm = NAN;
+
 	// publish uORB message
 	_rc_pub.publish(rc);
 }

src/modules/simulation/simulator_mavlink/SimulatorMavlink.cpp

@@ -913,6 +913,9 @@ void SimulatorMavlink::handle_message_rc_channels(const mavlink_message_t *msg)
 	rc_input.values[16] = rc_channels.chan17_raw;
 	rc_input.values[17] = rc_channels.chan18_raw;
 
+	rc_input.link_quality = -1;
+	rc_input.rssi_dbm = NAN;
+
 	rc_input.timestamp = hrt_absolute_time();
 
 	// publish message