rgblight: Fix rgblight_blink_layer when multiple layers are active

The change to support repeated blinking (qmk#12237) does not work correctly
when there are multiple blinking layers active at the same time.

It is decrementing the number of times remaining for every active layer
which will cause it to reach 0 prematurely and ignore some of the layers.

Decrement times remaining only once for each timer event.

quantum/rgblight/rgblight.c

@@ -825,18 +825,19 @@ void rgblight_blink_layer_repeat(uint8_t layer, uint16_t duration_ms, uint8_t ti
 void rgblight_blink_layer_repeat_helper(void) {
     if (_blinking_layer_mask != 0 && timer_expired(sync_timer_read(), _repeat_timer)) {
         for (uint8_t layer = 0; layer < RGBLIGHT_MAX_LAYERS; layer++) {
-            if ((_blinking_layer_mask & (rgblight_layer_mask_t)1 << layer) != 0 && _times_remaining > 0) {
+            if ((_blinking_layer_mask & (rgblight_layer_mask_t)1 << layer) != 0) {
                 if (_times_remaining % 2 == 1) {
                     rgblight_set_layer_state(layer, false);
                 } else {
                     rgblight_set_layer_state(layer, true);
                 }
-                _times_remaining--;
-                _repeat_timer = sync_timer_read() + _dur;
             }
         }
+        _times_remaining--;
         if (_times_remaining <= 0) {
             _blinking_layer_mask = 0;
+        } else {
+            _repeat_timer = sync_timer_read() + _dur;
         }
     }
 }