ArmVirtualizationPkg: use a HOB to store device tree blob

ArmVirtualizationPkg: use a HOB to store device tree blob

Instead of using a dynamic PCD, store the device tree address in a HOB
so that we can also run under a configuration that does not support
dynamic PCDs.

This also adds MemoryAllocationLib to the [LibraryClasses] section of
ArmVirtualizationPlatformLib/ArmVirtualizationPlatformLib.inf, as this
dependency was formerly satisfied transitively through one of the
library dependencies that were dropped.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16959 6f19259b-4bc3-4df7-8a09-765794883524