Fix (another) LeanbackPlayerAdapter param name mismatch

I missed this when fixing `positionInMs` for Dackka in d2a3d8f

This time I manually verified that all the `@Override` methods have
parameter names that match [the docs](https://developer.android.com/reference/androidx/leanback/media/PlayerAdapter).

#minor-release

PiperOrigin-RevId: 506017063
(cherry picked from commit 736f090)

Author: icbaker

extensions/leanback/src/main/java/com/google/android/exoplayer2/ext/leanback/LeanbackPlayerAdapter.java

@@ -110,9 +110,9 @@ public void onDetachedFromHost() {
   }
 
   @Override
-  public void setProgressUpdatingEnabled(boolean enabled) {
+  public void setProgressUpdatingEnabled(boolean enable) {
     handler.removeCallbacks(this);
-    if (enabled) {
+    if (enable) {
       handler.post(this);
     }
   }