fix(core): remove unnecessary fading

[no changelog]

Author: TychoVrahe

core/embed/io/display/display_utils.c

@@ -24,6 +24,9 @@
 
 void display_fade(int start, int end, int delay) {
 #ifdef USE_BACKLIGHT
+  if (display_get_backlight() == end) {
+    return;
+  }
   for (int i = 0; i < 100; i++) {
     display_set_backlight(start + i * (end - start) / 100);
     hal_delay(delay / 100);

core/embed/rust/src/ui/layout/simplified.rs

@@ -124,7 +124,7 @@ pub fn run(frame: &mut impl Component<Msg = impl ReturnToC>) -> u32 {
 pub fn show(frame: &mut impl Component, fading: bool) {
     frame.place(ModelUI::SCREEN);
 
-    if fading {
+    if fading && display::backlight() > 0 {
         ModelUI::fadeout()
     };