arm64: Add back print of processor name and rev

Add back print for the processor name and its rev id in c_show
function. This is required as some third party applications
need this field to be present. As cpu_name variable is removed
in a591ede4 ("arm64: Get rid of struct cpu_table"), directly
use "AArch64 Processor", to match original string, as cpu name.

Change-Id: I274ac72da8ec84c38ad04ff2b4009ac652b7b498
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>