Separate SiP related definition from mailbox header file

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I45ba540f29d9261007f7ec23469358747cf140b4

Pull out mailbox driver into common area as they can be shared between
intel's socfpga platform

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I4064de1ec668931d77abcb7804f6952b70d33716

Share socfpga private definitions and storage driver between Agilex and
Stratix 10 platform.

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I6da147f4d2df4a97c505d4bbcffadf63bc3bf4a5

Pull out handoff driver to intel/soc/ common directory as they can be
shared by both Agilex and Stratix10 platform.

Share platform_def header between both Agilex and Stratix10 and store
platform specific definitions in socfpga_plat_def.h

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I8eff1afd7ee71704a36a54fad732ede4f557878d

Pull out common code from aarch64 and include

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I4d0f5e1bb01bcdacbedf8e6c359de594239b645f