MIPS: make page.h constants available to assembly.

page.h includes ifndef __ASSEMBLY__ guards, but PAGE_SIZE and some other
constants are defined using "1UL", which the assembler does not support.
Use the _AC macro from const.h to make them available to assembly (and
linker scripts).

Signed-off-by: Nelson Elhage <nelhage@ksplice.com>
Signed-off-by: Tim Abbott <tabbott@ksplice.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>