arm: socfpga: Add handoff data support for Intel N5X device

N5X support both HPS handoff data and DDR handoff data.
Existing HPS handoff functions are restructured to support both existing
devices and N5X device.

Signed-off-by: Siew Chin Lim <elly.siew.chin.lim@intel.com>
Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>