Define LED_FUNCTION_PLAYER* if not defined (#1)

This change adds some preprocessor defines that were added to the Linux
kernel in 5.16. We simply define them if they're not already defined.
Even if this somehow slightly changes compatibility somehow, it's
harmless. It just affects a device name. Maybe someone's udev rule would
break. But the chances are extremely remote for reasons I don't want to
belabor here.

Fixes #1.

hid-nx.c

@@ -542,6 +542,15 @@ struct nx_con_input_report {
 
 static const unsigned short NX_CON_RUMBLE_ZERO_AMP_PKT_CNT = 5;
 
+/* for compat with kernels before 5.16 */
+#ifndef LED_FUNCTION_PLAYER1
+#define LED_FUNCTION_PLAYER1 "player-1"
+#define LED_FUNCTION_PLAYER2 "player-2"
+#define LED_FUNCTION_PLAYER3 "player-3"
+#define LED_FUNCTION_PLAYER4 "player-4"
+#define LED_FUNCTION_PLAYER5 "player-5"
+#endif
+
 static const char * nx_con_player_led_names[] = {
 	LED_FUNCTION_PLAYER1,
 	LED_FUNCTION_PLAYER2,