SystemUI: Fix NPE on creating taskview for controls ui

Fixes crash on launching A11 power menu with device controls.

Test
1) Set the power menu style to "Full (A11)".
2) Install the Google Home app.
3) Add your home to the device controls.
4) Long press the power button.

The power menu should open without crashing.

Change-Id: I6b7a96f75ef9b6b06491925a918122fdb2b0caad

packages/SystemUI/src/com/android/systemui/controls/ui/ControlsUiControllerImpl.kt

@@ -526,7 +526,7 @@ class ControlsUiControllerImpl @Inject constructor (
         val container = parent.requireViewById<FrameLayout>(R.id.controls_panel)
         container.visibility = View.VISIBLE
         container.post {
-            taskViewFactory.get().create(activityContext, uiExecutor) { taskView ->
+            taskViewFactory.get().create(activityContext ?: context, uiExecutor) { taskView ->
                 taskViewController = PanelTaskViewController(
                         activityContext ?: context,
                         uiExecutor,