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

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

boards/bitcraze/crazyflie/syslink/syslink_main.cpp

@@ -548,6 +548,9 @@ Syslink::handle_raw(syslink_message_t *sys)
 		rc.values[3] = cmd->thrust * 1000 / USHRT_MAX + 1000;
 		rc.values[4] = 1000; // Dummy channel as px4 needs at least 5
 
+		rc.link_quality = -1;
+		rc.rssi_dbm = NAN;
+
 		_rc_pub.publish(rc);
 
 	} else if (c->port == CRTP_PORT_MAVLINK) {

boards/emlid/navio2/navio_sysfs_rc_in/NavioSysRCInput.cpp

@@ -152,6 +152,9 @@ void NavioSysRCInput::Run()
 	data.timestamp_last_signal = timestamp_sample;
 	data.channel_count = CHANNELS;
 	data.input_source = input_rc_s::RC_INPUT_SOURCE_PX4FMU_PPM;
+	data.link_quality = -1;
+	data.rssi_dbm = NAN;
+
 	data.timestamp = hrt_absolute_time();
 
 	_input_rc_pub.publish(data);