stm32/mboot: Remove MP_WEAK on led funcs and make some of them static.

Both led_init and led_state are configurable via MBOOT_BOARD_LED_INIT and
MBOOT_BOARD_LED_STATE respectively, so don't need to be MP_WEAK.

Furthermore, led_state and led0_state are private to ui.c so can be made
static.
Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/mboot/ui.c

@@ -67,7 +67,7 @@ static led0_state_t led0_cur_state = LED0_STATE_OFF;
 static uint32_t led0_ms_interval = 0;
 static int led0_toggle_count = 0;
 
-MP_WEAK void led_init(void) {
+void led_init(void) {
     #if defined(MBOOT_BOARD_LED_INIT)
     // Custom LED init function provided by the board.
     MBOOT_BOARD_LED_INIT();
@@ -88,7 +88,7 @@ MP_WEAK void led_init(void) {
     led0_cur_state = LED0_STATE_OFF;
 }
 
-MP_WEAK void led_state(uint32_t led, int val) {
+static void led_state(uint32_t led, int val) {
     #if defined(MBOOT_BOARD_LED_STATE)
     // Custom LED state function provided by the board.
     return MBOOT_BOARD_LED_STATE(led, val);
@@ -115,7 +115,7 @@ void led_state_all(unsigned int mask) {
     #endif
 }
 
-void led0_state(led0_state_t state) {
+static void led0_state(led0_state_t state) {
     led0_cur_state = state;
     if (state == LED0_STATE_OFF || state == LED0_STATE_ON) {
         led_state(LED0, state);