nk3am: Remove blocking UP check

Since this commit [0] that changed the threshold from 3 to 1, the
blocking loop in the user presence check for the NK3AM does no longer
have any functional effect.  But it has undesired side effects, for
example skipping the UI update for a second so that the blinking effect
is not triggered, and delaying the handling of cancelled requests.

This patch removes the unnecessary blocking loop.  The button
implementation still requires 100 ticks to trigger a button press.

Fixes: #93

[0] 35dac8d

components/boards/src/nk3am/ui.rs

@@ -24,45 +24,7 @@ impl HardwareButtons {
 
 impl UserPresence for HardwareButtons {
     fn check_user_presence(&mut self, clock: &mut dyn Clock) -> consent::Level {
-        // essentially a blocking call for up to ~30secs
-        // this outer loop accumulates *presses* from the
-        // inner loop & maintains (loading) delays.
-
-        let mut counter: u8 = 0;
-        let threshold: u8 = 1;
-
-        let start_time = clock.uptime();
-        let timeout_at = start_time + Duration::from_millis(1_000);
-        let mut next_check = start_time + Duration::from_millis(25);
-
-        loop {
-            let cur_time = clock.uptime();
-
-            // timeout reached
-            if cur_time > timeout_at {
-                break;
-            }
-            // loop until next check shall be done
-            if cur_time < next_check {
-                continue;
-            }
-
-            if self.is_pressed(Button::A) {
-                counter += 1;
-                // with press -> delay 25ms
-                next_check = cur_time + Duration::from_millis(25);
-            } else {
-                // w/o press -> delay 100ms
-                next_check = cur_time + Duration::from_millis(100);
-            }
-
-            if counter >= threshold {
-                break;
-            }
-        }
-
-        // consent, if we've counted 3 "presses"
-        if counter >= threshold {
+        if self.is_pressed(Button::A) {
             consent::Level::Normal
         } else {
             consent::Level::None