MIPS: Add a CONFIG_FORCE_MAX_ZONEORDER Kconfig option.

MIPS: Add a CONFIG_FORCE_MAX_ZONEORDER Kconfig option.

For huge page support with base page size of 16K or 32K, we have to
increase the MAX_ORDER so that huge pages can be allocated.

[Ralf: I don't think a user should have to configure obscure constants like
this but for the time being this will have to suffice.]

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1685/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>