Staging: iio: Added define guards where needed

The following files were added define guards to prevent multiple
inclusion.

Signed-off-by: Cristina Opriceana <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/iio/Documentation/iio_utils.h

···
  * under the terms of the GNU General Public License version 2 as published by
  * the Free Software Foundation.
  */
+#ifndef _IIO_UTILS_H
+#define _IIO_UTILS_H
 
 #include <string.h>
 #include <stdlib.h>
···
 	free(temp);
 	return ret;
 }
+
+#endif /* _IIO_UTILS_H */

drivers/staging/iio/accel/sca3000.h

···
  * Can probably alleviate this by reading the interrupt register on start, but
  * that is really just brushing the problem under the carpet.
  */
+#ifndef _SCA3000
+#define _SCA3000
+
 #define SCA3000_WRITE_REG(a) (((a) << 2) | 0x02)
 #define SCA3000_READ_REG(a) ((a) << 2)
 
···
 }
 
 #endif
-
+#endif /* _SCA3000 */

drivers/staging/iio/frequency/dds.h

···
  *
  * Licensed under the GPL-2 or later.
  */
+#ifndef IIO_DDS_H_
+#define IIO_DDS_H_
 
 /**
  * /sys/bus/iio/devices/.../out_altvoltageX_frequencyY
···
 #define IIO_CONST_ATTR_OUT_WAVETYPES_AVAILABLE(_channel, _output, _modes)\
 	IIO_CONST_ATTR(							\
 	out_altvoltage##_channel##_out##_output##_wavetype_available, _modes)
+
+#endif /* IIO_DDS_H_ */

drivers/staging/iio/meter/meter.h

···
+#ifndef _METER_H
+#define _METER_H
+
 #include <linux/iio/sysfs.h>
 
 /* metering ic types of attribute */
···
 #define IIO_EVENT_ATTR_VPKLVL_EXC(_evlist, _show, _store, _mask) \
 	IIO_EVENT_ATTR_SH(vpklvl_exc, _evlist, _show, _store, _mask)
 
+#endif /* _METER_H */

drivers/staging/iio/resolver/ad2s1210.h

···
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#ifndef _AD2S1210_H
+#define _AD2S1210_H
 
 struct ad2s1210_platform_data {
 	unsigned sample;
···
 	unsigned res[2];
 	bool gpioin;
 };
+#endif /* _AD2S1210_H */