restore: Use %lx for map_files

map_files format defined as %lx-%lx in
kernel and while there should not be a
problem if it's written in %p-%p, still
better to be on a safe side and follow
kernel's notation.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>