bump XEN_DOMCTL_INTERFACE_VERSION

bump XEN_DOMCTL_INTERFACE_VERSION

Without this change valgrind can not decide what variant of
xen_domctl_createdomain is provided as input.

Fixes commit 4a83497635 ("xen/domctl: Merge set_max_evtchn into createdomain")
Fixes commit a903bf5233 ("tools: Pass grant table limits to XEN_DOMCTL_set_gnttab_limits")
Fixes commit ae8b8bc599 ("xen/domctl: Remove XEN_DOMCTL_set_gnttab_limits")
Fixes commit 4737fa52ce ("tools: Pass max_vcpus to XEN_DOMCTL_createdomain")

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Jan Beulich <jbeulich@suse.com>