[Keyboard] KBDfans/KBD75: Set "RGBLIGHT_SLEEP" as default (#7205)

keyboards/kbdfans/kbd75/config.h

@@ -44,4 +44,6 @@
 #define RGBLIGHT_HUE_STEP 8
 #define RGBLIGHT_SAT_STEP 8
 #define RGBLIGHT_VAL_STEP 8
+/* If defined, the RGB lighting will be switched off when the host goes to sleep */
+#define RGBLIGHT_SLEEP
 #endif