powerpc/ptdump: Display size of BATs

Display the size of areas mapped with BATs.

For that, the size display for pages is refactorised.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/acf764eee231f0358e66ca9e819f052804055acc.1589866984.git.christophe.leroy@csgroup.eu

powerpc: Move page table dump files in a dedicated subdirectory

This patch moves the files related to page table dump in a
dedicated subdirectory.

The purpose is to clean a bit arch/powerpc/mm by regrouping
multiple files handling a dedicated function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Shorten the file names while we're at it]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>