ArmVirtPkg: Kvmtool: Only install IORT if ITS is present

When the Kvmtool guest is launched without ITS support
i.e. when --irq-chip=gicv3-its option is not specified
or if --irq-chip=gicv3 is specified, the guest VM does
not have an ITS.

In such scenarios the guest firmware must not install
the IORT table. Therefore, add checks to see if ITS is
present before installing the IORT ACPI table.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>