Add common code dir for Matrix Vision boards.

This fixes current build failure.

Signed-off-by: Andre Schwarz <andre.schwarz@matrix-vision.de>

mvblm7.c: fix warning: implicit declaration of function
'mv_reset_environment'

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/matrix_vision/mvblm7/mvblm7.c b/board/matrix_vision/mvblm7/mvblm7.c
index b58c1b9..6a4ed52 100644
--- a/board/matrix_vision/mvblm7/mvblm7.c
+++ b/board/matrix_vision/mvblm7/mvblm7.c
@@ -34,6 +34,7 @@
 #include <libfdt.h>
 #endif
 
+#include "../common/mv_common.h"
 #include "mvblm7.h"
 
 int fixed_sdram(void)