Rename methods to reflect the correct names of nav modes

Bug: 146004827
Test: make RunSettingsRoboTests ROBOTEST_FILTER=SystemNavigationGestureSettingsTest
Test: make RunSettingsRoboTests ROBOTEST_FILTER=SystemNavigationPreferenceControllerTest

Change-Id: I00602c41aed5e675b8e0d3df7a3b3b318e6ec903
3 files changed