Removed an extraneous messge when pairing.

+ When two devices are executing Bluetooth simply pairing, which does
not need keyboard input, the message "Type the pairing code then press
Return or Enter." has been removed.
+ Note that in legacy pairing the message to type in the pairing key
should remain even if the user is only verifying the key.  The reason is
that we are not able to guarantee the other device does not have to input
the key.
+ Also updated pin entry to Material/Quantum specification.

Bug: 17400402
Change-Id: I7853fa13835f7f60d0e71102de9a079708f3544e