m68k: Add export.h to the m68k specific files as required

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/m68k/kernel/dma_mm.c b/arch/m68k/kernel/dma_mm.c
index 4bbb3c2..a3c471b 100644
--- a/arch/m68k/kernel/dma_mm.c
+++ b/arch/m68k/kernel/dma_mm.c
@@ -12,6 +12,7 @@
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <linux/export.h>
 
 #include <asm/pgalloc.h>