[LockScreen] Don't extract UI in ChooseLockPassword

Added flagnoextractui to the EditText in ChooseLockPasswordActivity
so that the instruction text is still visible on phone landscape.
Also wrapped it in a ScrollView because for smaller screen devices
the buttons may be squeezed to fit onto the screen if the ScrollView
is not there.

Bug: 18644582
Change-Id: Ib81aadb5377aacc8d85fdeee7e1809ad3ff71213