sh: Add support Renesas Solutions R2D plus board

R2D plus is SH reference board used with SH7751R.
This board has 266Mhz CPU, 64MB SDRAM, Cardbus, CF interface,
one PCI bus, VGA, and two Ethernet controller.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 5471c1d..39743c7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -698,6 +698,7 @@
 
 	MS7750SE		SH7750
 	MS7722SE		SH7722
+	R2DPlus			SH7751R
 
 Mark Jonas <mark.jonas@de.bosch.com>