Update string displayed on work pin/password challenge

* The incorrect string was being displayed when the user
  was asked to enter their pin/password.
* Updated the string to include **work** instead of
  **device** when entering a work pin/password.

Bug: 148211118
Test: Manual testing
Change-Id: I2239a5011dec62fd63574bbf75495548ddd0d907
2 files changed