Revert "xen/pvh: Update E820 to work with PVH (v2)"

This reverts commit 9103bb0f.

Now than xen_memory_setup() is not called for auto-translated guests,
we can remove this commit.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>