staging:iio:iio_utils.h: Add missing include

iio_utils.h uses opendir and friends which need dirent.h
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Documentation/iio_utils.h

@@ -13,6 +13,7 @@
 #include <ctype.h>
 #include <stdio.h>
 #include <stdint.h>
+#include <dirent.h>
 
 #define IIO_MAX_NAME_LENGTH 30