Fix 2572446: Also watch keyboard changes in PIN/Password unlock.
The PIN/Password unlock screen was monitoring orientation changes.
However, while docked, this isn't useful since orientation remains
fixed. This change makes PasswordUnlockScreen also looks for
changes to config.hardKeyboardHidden.
Tested:
WVGA device while docked and opening/closing the keyboard.
Change-Id: Iaadb277028f2dd1f85fd0f627a686a86ac51a2ed
5169fc57e3