ppc: synchronize excp_vectors for injecting exception

This patch synchronizes env->excp_vectors[] with env->iovr[].
This is required for using the existing interrupt injection mechanism
for kvm.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
