Fixed crash when opening Camera Lift suggestion

Bug: 37742959
Test: manual + make RunSettingsRoboTests +
      adb shell am instrument -w com.android.settings.tests.unit
          /android.support.test.runner.AndroidJUnitRunner

Added missing SettingsGateway entry for Camera Lift Trigger settings
fragment.

Change-Id: Iddce7a672b0bb8430e3c7b3c346788fb23970636