ArmVirtPkg: Kvmtool: Add RNG support using Arm TRNG interface

Bugzilla: 3668 (https://bugzilla.tianocore.org/show_bug.cgi?id=3668

)

The EFI_RNG_PROTOCOL published by RngDxe has been updated to
implement the EFI_RNG_ALGORITHM_RAW using the Arm TRNG interface
to provide access to entropy.

Therefore, enable EFI_RNG_PROTOCOL for the Kvmtool guest/virtual
firmware.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>