NUMA: replace phys_to_nid()

NUMA: replace phys_to_nid()

All callers convert frame numbers (perhaps in turn derived from struct
page_info pointers) to an address, just for the function to convert it
back to a frame number (as the first step of paddr_to_pdx()). Replace
the function by mfn_to_nid() plus a page_to_nid() wrapper macro. Replace
call sites by the respectively most suitable one.

While there also
- introduce a !NUMA stub, eliminating the need for Arm (and potentially
  other ports) to carry one individually,
- drop the (strictly speaking wrong) "pure" attribute from the function,
- extend a condition in dump_numa() to make sure that none of the
  assertions would trigger for empty or (unlikely) single-page nodes (at
  the same time this also prevents the warning printk() to be issued for
  every empty [e.g. CPU-only] node).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>