x86/xen: add reschedule point when mapping foreign GFNs
x86/xen: add reschedule point when mapping foreign GFNs

Mapping a large range of foreign GFNs can take a long time, add a
reschedule point after each batch of 16 GFNs.

Signed-off-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>
Reviewed-by: Boris Ostrovsky <b41c17b861974b03cec38e3ec2992769b9bfae55@oracle.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs