arm64: Add support to print hardware id info

Initial support to print hardware id is added with
commit 'eab25833f0d4 ("ARM/ARM64: Introduce 
arch_read_hardware_id")', with recent down port 
changes, this print hardware info is missed to propagate.
Adding it back with defining common variables in header file.

Change-Id: I4da63bd2346c0d0296087941967ae1a98eb6d86f
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>