xen/arm: mm: Introduce DEFINE_PAGE_TABLE{,S} and use it

xen/arm: mm: Introduce DEFINE_PAGE_TABLE{,S} and use it

We have multiple static page-tables defined in arch/arm/mm.c. The
current way to define them is difficult to read and does not help when
making modification.

Two new helpers DEFINE_PAGE_TABLES (to define multiple page-tables) and
DEFINE_PAGE_TABLE (alias of DEFINE_PAGE_TABLES(..., 1)) are introduced
and now used to define static page-tables.

Note that DEFINE_PAGE_TABLES() alignment differs from what is currently
used for allocating page-tables. This is fine because page-tables are
only required to be aligned to a page-size.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>