KVM: ia64: Map in SN2 RTC registers to the VMM module

On SN2, map in the SN2 RTC registers to the VMM module, needed for ITC
emulation.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>