Fix NPE crashes during UDFPS BiometricPrompt

BiometricPrompt for UDFPS used to be working by coincidence. We were
always passing null into non-null places. Just it actually broke now.

Fixes: 181884785
Test: manual
Test: atest com.android.systemui.biometrics
Change-Id: Iae22966f0a3ea0bfc543cd01e4b3373d1cead937