hwmon: (max197) add include guard

Add include guard to include/linux/platform_data/max197.h to prevent
multiple inclusion.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

include/linux/platform_data/max197.h

@@ -11,6 +11,9 @@
  * For further information, see the Documentation/hwmon/max197 file.
  */
 
+#ifndef _PDATA_MAX197_H
+#define _PDATA_MAX197_H
+
 /**
  * struct max197_platform_data - MAX197 connectivity info
  * @convert:	Function used to start a conversion with control byte ctrl.
@@ -19,3 +22,5 @@
 struct max197_platform_data {
 	int (*convert)(u8 ctrl);
 };
+
+#endif /* _PDATA_MAX197_H */