Sleep Timer: Change time step to 1 minute (Closes #14611)

Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>

Sources/VLCMovieViewController.m

@@ -408,7 +408,7 @@ typedef NS_ENUM(NSInteger, VLCPanType) {
         }
     }
     _sleepTimeDatePicker.datePickerMode = UIDatePickerModeCountDownTimer;
-    _sleepTimeDatePicker.minuteInterval = 5;
+    _sleepTimeDatePicker.minuteInterval = 1;
     _sleepTimeDatePicker.minimumDate = [NSDate date];
     _sleepTimeDatePicker.countDownDuration = 1200.;
     [_sleepTimeDatePicker addTarget:self action:@selector(sleepTimerAction:) forControlEvents:UIControlEventValueChanged];