8xx, mgsuvd: rename board to a more generic name

renaming the "mgsuvd" board port into "km8xx", because
there come more similar boards from keymile.
Compiling the mgsuvd board with "make mgsuvd_config"
remains.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/Makefile b/Makefile
index 180d2f5..859dfb7 100644
--- a/Makefile
+++ b/Makefile
@@ -938,7 +938,7 @@
 	@$(MKCONFIG) $(@:_config=) ppc mpc8xx mbx8xx
 
 mgsuvd_config:		unconfig
-	@$(MKCONFIG) $(@:_config=) ppc mpc8xx mgsuvd keymile
+	@$(MKCONFIG) $(@:_config=) ppc mpc8xx km8xx keymile
 
 MHPC_config:		unconfig
 	@$(MKCONFIG) $(@:_config=) ppc mpc8xx mhpc eltec