Udfps enrollment now focuses on fingerprint region

Test: Verified manually that the region that accesibility focuses on is
around the fingerprint sensor.
Test: Verified in landscape/reverse landscape/portrait & with/without accessibility
enabled.
Bug: 195614793

Change-Id: I2be5e5bf657254e843dc863afa56318708ec3411
(cherry picked from commit 2b229d14)