xen/gnttab: Pass max_{grant,maptrack}_frames into grant_table_create()

xen/gnttab: Pass max_{grant,maptrack}_frames into grant_table_create()

... rather than setting the limits up after domain_create() has completed.

This removes the common gnttab infrastructure for calculating the number of
dom0 grant frames (as the common grant table code is not an appropriate place
for it to live), opting instead to require the dom0 construction code to pass
a sane value in via the configuration.

In practice, this now means that there is never a partially constructed grant
table for a reference-able domain.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>