meson/gxl: Configure and boot SCP ...

On Amlogic gxl (s905x) SOC, in order to use SCP, bl31 has to send bl30
and bl301 firmware along with their SHA256 hash over scpi.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>

meson/gxl: Add support for SHA256 DMA engine ...

In order to configure and boot SCP, BL31 has to compute and send
the SHA-256 of the firmware data via scpi. Luckily Amlogic GXL SOC
has a DMA facility that could be used to offload SHA-256
computations. This adds basic support of this hardware SHA-256
engine.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>

meson/gxl: Initial port of Amlogic Meson S905x (GXL) ...

The Amlogic Meson S905x is a SoC with a quad core Arm Cortex-A53 running
at 1.5Ghz. It also contains a Cortex-M3 used as SCP.

This port is a minimal implementation of BL31 capable of booting
mainline U-Boot and Linux:

- Partial SCPI support.
- Basic PSCI support (CPU_ON, SYSTEM_RESET, SYSTEM_OFF).
- GICv2 driver set up.
- Basic SIP services (read efuse data, enable/disable JTAG).

This port has been tested on a lepotato.

Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Remi Pommarel <repk@triplefau.lt>