include: don't use asm/page.h from common headers

include: don't use asm/page.h from common headers

Doing so limits what can be done in (in particular included by) this per-
arch header. Abstract out page shift/size related #define-s, which is all
the respective headers care about. Extend the replacement / removal to
some x86 headers as well; some others now need to include page.h (and
they really should have before).

Arm's VADDR_BITS gets dropped altogether: Its current value is clearly
wrong for 64-bit, but the constant also isn't used anywhere right now.

While Arm used vaddr_t in PAGE_OFFSET(), this use is compatible with
that of unsigned long in the new common implementation.

Also drop the dead PAGE_FLAG_MASK at this occasion.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>