md: Add in export.h for files using EXPORT_SYMBOL

These files were getting the defines for EXPORT_SYMBOL because
device.h was including module.h.  But we are going to put an
end to that.  So add the proper export.h include now.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/lib/raid6/mktables.c b/lib/raid6/mktables.c
index 3b15008..8a37809 100644
--- a/lib/raid6/mktables.c
+++ b/lib/raid6/mktables.c
@@ -60,6 +60,7 @@
 	uint8_t exptbl[256], invtbl[256];
 
 	printf("#include <linux/raid/pq.h>\n");
+	printf("#include <linux/export.h>\n");
 
 	/* Compute multiplication table */
 	printf("\nconst u8  __attribute__((aligned(256)))\n"