The definitions in include/asm/xen/page.h are arch specific.
ia64/xen wants to define its own version. So move them to arch specific
directory and keep include/xen/page.h in order not to break compilation.

Signed-off-by: Isaku Yamahata
Signed-off-by: Jeremy Fitzhardinge
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner