ArmVirtPkg: Enable Virtio communication for Arm CCA

Arm CCA Realms protect the access to memory from outside the
Realm. For Virtio to work the Realm Guest and the Host should
be able to share buffers.

Realm Aperture Management protocol (RAMP) manages the sharing
of buffers between the Realm Guest and the Host, while the
ArmCcaIoMmuDxe implements the EDKII_IOMMU_PROTOCOL which
provides the necessary hooks so that DMA accesses can be
performed by bouncing buffers using pages shared with the
host.

Therefore, enable the support for Realm Aperture Management
Protocol and ArmCcaIoMmuDxe for Kvmtool Guest firmware.

Note: The ArmCcaIoMmuDxe and RAMP check if the code is executing
in a Realm before installing the respective protocols. If the
code is not executing in a Realm the gIoMmuAbsentProtocolGuid is
installed, thereby allowing the same firmware to be used both for
normal and Realm Guest firmware.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>