block/xen-blkfront: Store a page rather a pfn in the grant structure
block/xen-blkfront: Store a page rather a pfn in the grant structure

All the usage of the field pfn are done using the same idiom:

pfn_to_page(grant->pfn)

This will  return always the same page. Store directly the page in the
grant to clean up the code.

Signed-off-by: Julien Grall <2fe41d4e32b0bb991f63b975f2bed08c1e666665@citrix.com>
Acked-by: Roger Pau Monné <1c35b25b17252e1e5021df00666589fc74f64580@citrix.com>
Reviewed-by: Stefano Stabellini <22a0c6385d750d07aa383c9f813cf6f0228657d8@eu.citrix.com>
Signed-off-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>

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