staging: iio: generic_buffer: initialize ret

The `ret´ variable is only initialized in the error case. For some reason
it was always != 0 while I played with generic_buffer so here is a patch.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/Documentation/iio_utils.h

@@ -502,7 +502,7 @@ inline int find_type_by_name(const char *name, const char *type)
 
 inline int _write_sysfs_int(char *filename, char *basedir, int val, int verify)
 {
-	int ret;
+	int ret = 0;
 	FILE *sysfsfp;
 	int test;
 	char *temp = malloc(strlen(basedir) + strlen(filename) + 2);