xen: Convert kmap() to kmap_local_page()

kmap() is being deprecated and these usages are all local to the thread
so there is no reason kmap_local_page() can't be used.

Replace kmap() calls with kmap_local_page().

Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220419234328.10346-1-eng.alaamohamedsoliman.am@gmail.com


Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>