xen: introduce PHYSDEVOP_pirq_eoi_gmfn_v2

xen: introduce PHYSDEVOP_pirq_eoi_gmfn_v2

PHYSDEVOP_pirq_eoi_gmfn changes the semantics of PHYSDEVOP_eoi.
In order to improve the interface this patch:

- renames PHYSDEVOP_pirq_eoi_gmfn to PHYSDEVOP_pirq_eoi_gmfn_v1;

- introduces PHYSDEVOP_pirq_eoi_gmfn_v2, that is like
  PHYSDEVOP_pirq_eoi_gmfn_v1 but it doesn't modify the behaviour of
  another hypercall;

- bump __XEN_LATEST_INTERFACE_VERSION__;

- #define PHYSDEVOP_pirq_eoi_gmfn to PHYSDEVOP_pirq_eoi_gmfn_v1 or
  PHYSDEVOP_pirq_eoi_gmfn_v2 depending on the __XEN_INTERFACE_VERSION.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Keir Fraser <keir@xen.org>