ArmVirtPkg: align ArmVirtQemuKernel with ArmVirtQemu

ArmVirtPkg: align ArmVirtQemuKernel with ArmVirtQemu

The platform ArmVirtQemuKernel is intended as an alternative for
ArmVirtQemu that only deviates in the way it is invoked by QEMU, either
from flash address 0x0 (the default ARM reset vector) or via the Linux
kernel boot protocol. So add VirtioRngDxe and HighMemDxe here as well.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>