Add emergency call button to PUK'd lockscreen.

The user unlocks a PUK-locked SIM via the e-call dialer, so
we absolutely need the button there.

This is the layout portion; it requires change
I6872c3ad135bc34348adafa76e08a3878f1b506f from
frameworks/policies/base.

Bug: 2568732
Change-Id: I8aa0fc2223428ba15a57269ac5a624e74e91a5f3