[Keyboard] Allow user override of RGB_DISABLE_WHEN_USB_SUSPENDED for BM40 keyboard (#12700)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: filterpaper <filterpaper@localhost>

keyboards/bm40hsrgb/config.h

@@ -50,6 +50,6 @@
 #ifdef RGB_DI_PIN
     #define RGB_MATRIX_KEYPRESSES // reacts to keypresses
 #endif
-#ifdef RGB_MATRIX_ENABLE
+#ifndef RGB_DISABLE_WHEN_USB_SUSPENDED
 #    define RGB_DISABLE_WHEN_USB_SUSPENDED true // turn off effects when suspended
 #endif