drivers/dca: Add export.h for THIS_MODULE to dca-sysfs.c

Ensure we have access to the THIS_MODLUE macro once we clean up
the implicit module.h usage.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

drivers/dca/dca-sysfs.c

@@ -27,6 +27,7 @@
 #include <linux/err.h>
 #include <linux/dca.h>
 #include <linux/gfp.h>
+#include <linux/export.h>
 
 static struct class *dca_class;
 static struct idr dca_idr;