Remove empty override functions (#14312)

* Remove empty override functions, 0-9

* Remove empty override functions, A-D

* Remove empty override functions, E-H

* Remove empty override functions, handwired

* Remove empty override functions, I-L

* Remove empty override functions, M-P

* Remove empty override functions, Q-T

* Remove empty override functions, U-Z

keyboards/handwired/frenchdev/keymaps/default/keymap.c

@@ -205,9 +205,6 @@ void press_underscore(void) {
   if(shift_count > 0) register_code (KC_LSHIFT);
 }
 
-void matrix_init_user(void) {
-}
-
 // Bleah globals need to be initialized.
 uint8_t old_layer=_BASE;