8641hpcn: Fix Makefile after moving pixis to board/freescale.

The OBJTREE != SRCTREE build scenario was broken.
This fixes it.

Signed-off-by: Ed Swarthout <Ed.Swarthout@freescale.com>
Signed-off-by: Jon Loeliger <jdl@freescale.com>
diff --git a/board/mpc8641hpcn/Makefile b/board/mpc8641hpcn/Makefile
index 9625211..df56b31 100644
--- a/board/mpc8641hpcn/Makefile
+++ b/board/mpc8641hpcn/Makefile
@@ -23,6 +23,10 @@
 
 include $(TOPDIR)/config.mk
 
+ifneq ($(OBJTREE),$(SRCTREE))
+$(shell mkdir -p $(obj)../freescale/common)
+endif
+
 LIB	= $(obj)lib$(BOARD).a
 
 COBJS	:= $(BOARD).o sys_eeprom.o \