Wait a bit for devices to initialize before trying to enumerate and open them.

This works around udev event nodes arriving before hidraw nodes and the controller being opened twice - once using the Linux driver and once by the HIDAPI driver.

This also fixes a kernel panic on Steam Link hardware due to trying to open the hidraw device node too early.

A delay of 10 ms seems to be a good value, tested on Steam Link hardware.

src/joystick/linux/SDL_sysjoystick.c

@@ -267,6 +267,10 @@ static void joystick_udev_callback(SDL_UDEV_deviceevent udev_type, int udev_clas
                     return;
                 }
             }
+
+            /* Wait a bit for the hidraw udev node to initialize */
+            SDL_Delay(10);
+
             MaybeAddDevice(devpath);
             break;