regulator: fan53555: Prevent multiple include of fan53555.h

Add define for __FAN53555_H__ to prevent multiple include of the header file.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/linux/regulator/fan53555.h

@@ -11,6 +11,7 @@
  */
 
 #ifndef __FAN53555_H__
+#define __FAN53555_H__
 
 /* VSEL ID */
 enum {