Fix feedback for main haptic settings toggle

The SettingsMainSwitchPreferenceController might trigger a state change
twice on the page main switch when the user toggles the setting value.

Make sure we only trigger haptic feedback when the state is changing
between untoggled to toggled to avoid a double-click feedback.

No flag for small bug fix, no UI changes.

Fix: 338334977
Test: enable the "Use vibration & haptics" settings and feel a single
      click feedback
Change-Id: I0c22b99bcb40f35ebe09c153133c354306ed1ff0