Add support for arm64

Depends on corresponding API change in user space.

* Adds support for arm64
* Many small fixes to make generic code compile for arm64
* Moves teesmc*.h from armv7 specific to include/arm_common
Add fdts for FVP Foundation model

Adds fdts for FVP Foundation model which reserves the shared
memory used by normal and secure world.

These files is a temporary workaround until the driver has switched
to use CMA to allocate shared memory.