Remove the getSwitch() in SwitchWidgetController

IMHO we don't need to expose switch in SwitchWidgetController.
This controller already has enough API to control the switch.

Also rename mSwitchWidget to mSwitchController because it is not a
widget.

Bug: 69973752
Test: test still pass
Change-Id: I0ac247e34468a44109ab26019f1303c814e381f2

src/com/android/settings/widget/MasterSwitchController.java

@@ -74,9 +74,4 @@ public class MasterSwitchController extends SwitchWidgetController implements
     public void setDisabledByAdmin(EnforcedAdmin admin) {
         mPreference.setDisabledByAdmin(admin);
     }
-
-    @Override
-    public Switch getSwitch() {
-        return mPreference.getSwitch();
-    }
 }