MIPS: Add CONFIG_CPU_R5500 for NEC VR5500 series processors

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: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 9798660..9316324 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -192,6 +192,7 @@
 #define PM_16M		0x01ffe000
 #define PM_64M		0x07ffe000
 #define PM_256M		0x1fffe000
+#define PM_1G		0x7fffe000
 
 #endif