sh: sh3: Move to boards.cfg

Move the sh3 target boards out of the Makefile and into boards.cfg.
And fix sh3 of MAKEALL.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/MAKEALL b/MAKEALL
index a97061c..71dcba2 100755
--- a/MAKEALL
+++ b/MAKEALL
@@ -610,11 +610,7 @@
 #########################################################################
 
 LIST_sh2="$(boards_by_cpu sh2)"
-
-LIST_sh3="		\
-	mpr2		\
-	ms7720se	\
-"
+LIST_sh3="$(boards_by_cpu sh3)"
 
 LIST_sh4="		\
 	ms7750se	\