MIPS: Kconfig Add SYS_SUPPORTS_HUGETLBFS and enable it for some systems.

Add new kconfig variables SYS_SUPPORTS_HUGETLBFS and
CPU_SUPPORTS_HUGEPAGES.  They are enabled for systems that are known
to support huge pages.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>