Support for Mediatek MT6795 SoC ...

This patch support single core to boot to Linux kernel
through Trusted Firmware.
It also support 32 bit kernel and 64 bit kernel booting.

mt8173: Reorganize plat SiP functions ...

Due to the changes in Mediatek platform common code, we need to move
plat related SiP functions to plat folder.

Change-Id: I6b14b988235205a5858b4bf49043bc79d0512b06
Signed-off-by: Jimmy Huang <jimmy.huang@mediatek.com>

Refactor MediaTek platform common code ...

Refactor MediaTek platform common code for further mt6795 upstream.

mt8173: Implement subsystem power control logic in ARM TF ...

1. Add SiP calls for subsystem power on/off and check support
2. Add subsystem power control related initialization in
   bl31_plat_setup.c
3. Add subsystem power on/off and power ack waiting functions
4. Update PCM code for subsystem physical power control logic

Change-Id: Ia0ebb1964c8f9758159bcf17c1813d76ef52cf64
Signed-off-by: yt.lee <yt.lee@mediatek.com>

Initial platform port for MediaTek mt8173 ...

- Boot up 4 cores.
- Add a generic UART driver.
- Add generic CPU helper functions
- Supoort suspend
- Add system_off & system_reset implementation
- Add crash console reporting implementation
- Add get_sys_suspend_power_state() for PSCI 1.0 SYSTEM_SUSPEND
- Add Mediatek SIP runtime service
- Add delay timer platform implementation

Change-Id: I44138249f115ee10b9cbd26fdbc2dd3af04d825f
Signed-off-by: CC Ma <cc.ma@mediatek.com>
Signed-off-by: Jimmy Huang <jimmy.huang@mediatek.com>