Add support for arm Foundation ARMv8 FVP simulator

Add recipes and configuration files to add Yocto support
for Foundation armv8 simulator from arm.
The following components are supported:
- trusted-firmware-a
- linux kernel (with specific kernel configuration)
- xen (with meta-virtualization layer)
- unpacking and starting the generated image directly in Foundation
simulator (package must be download from www.arm.com website and put in
the directory downloads/licensed/silver.arm.com).

After building, the following command can be used to start a generated
image in foundation:
./tmp/deploy/tools/start-foundation-armv8.sh

Change-Id: Iade343c38f0799ee8523434d555cb3ca42068a86
Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>

meta-arm-bsp/documentation/foundation-armv8.md

@@ -0,0 +1,36 @@
+# Armv8-A Base Platform Support in meta-arm-platforms
+
+## Howto Build and Run
+
+### Configuration:
+In the local.conf file, MACHINE should be set as follow:
+MACHINE ?= "foundation-v8"
+
+### Build:
+```bash$ bitbake core-image-minimal```
+
+### Run:
+The layer provides a recipe to install the Armv8-A Foundation Platform in your
+environment. You must download Armv8-A Foundation Platform from Arm developer
+(This might require the user to register) from this address:
+https://developer.arm.com/tools-and-software/simulation-models/fixed-virtual-platforms
+and put the downloaded tar file in 'downloads/licensed/silver.arm.com/'
+directory of your project (or of your Pre-Mirror if you have one).
+
+Once done, do the following to build and run an image:
+```bash$ bitbake core-image-minimal```
+```bash$ ./tmp/deploy/tools/start-foundation-armv8.sh```
+
+If you have built a configuration without a ramdisk, you can use the following
+command in U-boot to start Linux:
+```VExpress64# booti 0x80080000 - 0x83000000```
+
+## Devices supported in the kernel
+- serial
+- virtio disk
+- network
+- watchdog
+- rtc
+
+## Devices not supported or not functional
+None