Port 4.4 suspend code into TF-A

- Import register layout, flag definitions, etc. from 4.4
- Import low-power core firmware
- Copy register settings and control flow from 4.4
- Fix a bug on resume where the wrong initialization was called for the
interrupt controller.

Change-Id: Ia32717f7b6715b85370a382fa343a474d5fbb20a
7 files changed