edac: cortex: Snapshot arm64 cortex-a cpu edac driver

This is a snapshot of arm64 cortex-a cpu edac driver from
msm-4.4 commit a9a0da48eb3f (Merge "edac: cortex: Remove
 WARN_ON messages"). Below are the changes are done on top
of that to get compiled.

1. #define ARM_CPU_PART_KRYO2XX_GOLD      0x800
   #define ARM_CPU_PART_KRYO2XX_SILVER    0x801

2. register_cpu_notify() have been replaced with CPU hotplug
state-machine.

Change-Id: Ic84ceb52114947f17fc6d0fac87039d4b450f70a
Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>