[U-Boot] [PATCH] fix broken matrix vision boards

boards are currently broken due to missing common dir inside board dir.

MATRIX VISION GmbH, Talstrasse 16, DE-71570 Oppenweiler Registergericht: Amtsgericht Stuttgart, HRB 271090 Geschaeftsfuehrer: Gerhard Thullner, Werner Armingeon, Uwe Furtner, Hans-Joachim Reich