rpi3: Add support for Trusted Board Boot ...

This patch adds support for TBB to rpi3. The ROTPK is generated at build
time and is included into BL1/BL2. The key and content certificates are
read over semihosting.

Tested-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>

rpi3: add OPTEE support ...

Support for loading optee images as BL32 secure payload.

Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>

rpi3: Use new console APIs ...

Switch to the new console APIs enabled by setting MULTI_CONSOLE_API=1.

The crash console doesn't use this API, it uses internally the core
functions of the 16550 console.

`bl31_plat_runtime_setup` is no longer needed. When this platform port
was introduced, that function used to disable the console. It was needed
to override that behaviour. The new behaviour is to switch to the
runtime console. The console is registered for all scopes (boot, crash
and runtime) in `rpi3_console_init` so it is not needed to override the
default behaviour anymore.

Update documentation.

Change-Id: If2ee8f91044216183b7ef142e5c05ad6220ae92f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Disable workaround for CVE-2017-5715 on unaffected platforms ...

Change-Id: Ib67b841ab621ca1ace3280e44cf3e1d83052cb73
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

rpi3: Introduce AArch64 Raspberry Pi 3 port ...

This port can be compiled to boot an AArch64 or AArch32 payload with the
build option `RPI3_BL33_AARCH32`.

Note: This is not a secure port of the Trusted Firmware. This port is
only meant to be a reference implementation to experiment with an
inexpensive board in real hardware.

Change-Id: Ide58114299289bf765ef1366199eb05c46f81903
Co-authored-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>