KVM: PPC: e500: emulate SVR

Return the actual host SVR for now, as we already do for PVR.  Eventually
we may support Qemu overriding PVR/SVR if the situation is appropriate,
once we implement KVM_SET_SREGS on e500.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>