Added string to encourage user to enroll more fingerprints

Test: Manual - Finish enrolling a fingerprint and check the message
displayed
Bug: 265023475

Change-Id: I77a6bd08a5bfb58971539bf4d366d0425ae0c9a0
Merged-in: I77a6bd08a5bfb58971539bf4d366d0425ae0c9a0
2 files changed