Fix duplicate onFingerDown calls in UdfpsController

On certain devices, touches are received by both AOD and
UdfpsOverlay. Add check for mOnFingerDown to prevent sending duplicate
onFingerDown calls to HAL.

Bug: 293749415
Test: Manual, verified expected behavior on AOD and Keyguard
Test: atest UdfpsControllerTest

Change-Id: I28b5d736a234ef8c8cff4fbce6b6bf771f75917a
2 files changed