KVM: PPC: Book3S PR: Handle additional interrupt types

This adds trivial handling for additional interrupt types that KVM-PR must
support for proper virtualization on a POWER9 host in HPT mode, as a further
prerequisite to enabling KVM-PR on that configuration.

Signed-off-by: Cameron Kaiser <spectre@floodgap.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>