Remove unnecessary assignment in PlayerControlView

This was highlighted by a compilation failure when migrating to Guava's
`Preconditions` methods.

PiperOrigin-RevId: 791159654

Author: icbaker

libraries/ui/src/main/java/androidx/media3/ui/PlayerControlView.java

@@ -929,7 +929,7 @@ public void setExtraAdGroupMarkers(
       this.extraAdGroupTimesMs = new long[0];
       this.extraPlayedAdGroups = new boolean[0];
     } else {
-      extraPlayedAdGroups = checkNotNull(extraPlayedAdGroups);
+      checkNotNull(extraPlayedAdGroups);
       Assertions.checkArgument(extraAdGroupTimesMs.length == extraPlayedAdGroups.length);
       this.extraAdGroupTimesMs = extraAdGroupTimesMs;
       this.extraPlayedAdGroups = extraPlayedAdGroups;