gps driver: added more baud rates in order to support bebop2

Signed-off-by: Roman <bapstroman@gmail.com>

src/drivers/gps/gps.cpp

@@ -510,6 +510,8 @@ int GPS::setBaudrate(unsigned baud)
 	int speed;
 
 	switch (baud) {
+	case 4800:   speed = B4800;   break;
+
 	case 9600:   speed = B9600;   break;
 
 	case 19200:  speed = B19200;  break;
@@ -520,6 +522,8 @@ int GPS::setBaudrate(unsigned baud)
 
 	case 115200: speed = B115200; break;
 
+	case 230400: speed = B230400; break;
+
 	default:
 		PX4_ERR("ERR: unknown baudrate: %d", baud);
 		return -EINVAL;