rename XENMEM_add_to_physmap_{range => batch}

rename XENMEM_add_to_physmap_{range => batch}

The use of "range" here wasn't really correct - there are no ranges
involved. As the comment in the public header already correctly said,
all this is about is batching of XENMEM_add_to_physmap calls (with
the addition of having a way to specify a foreign domain for
XENMAPSPACE_gmfn_foreign).

Suggested-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>