Inform the falsing manager about UDFPS touches on down

Instead of up/cancel. The new UDFPS touch handling doesn't
receive the up/cancel events until after the falsing manager
has already evaluated the touch as a false vs valid touch,
so UDFPS touches were penalizing the falsing confidence
too much.

Test: atest UdfpsControllerTest
Test: manually enable falsing logs and see that UDFPS touches
don't greatly increase the falsing confidence of the FalsingManager
(adb shell setprop log.tag.FalsingManager DEBUG)
Fixes: 288235975

Change-Id: Ic4b8b0b52343d357e0c807bede64598836d159b0