feat(mediatek): introduce mtk init framework

Provide six initcall levels for drivers/modules initialize HW
controllers or runtime arguments during cold boot.

The initcall level cold boot execution order:

Call before MMU enabled.

MMU Enabled, arch related init(GiC init, interrupt type registration).

MTK driver init level 0.

MTK driver init level 1.

MTK driver init. After this initcall, TF-A handovers to MTK 2nd

MTK 2nd bootloader traps to TF-A before handover to rich OS.
This initcall executed in the trap handler(boot_to_kernel).

Signed-off-by: Leon Chen <leon.chen@mediatek.com>
Change-Id: Icd7fe95372441db73c975ccb6ce77a6c529df1cc
9 files changed