We already have sufficient infrastructure to support VR5500 and VR5500A
series processors.  Here's a Makefile support to make it selectable by
ports, and enable it for NEC EMMA2RH Markeins board.

This patch also fixes a confused target help, and adds 1Gb PageMask bits
supported by VR5500 and its variants.
Signed-off-by: NShinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>