iio: Make IIO value formating function globally available.

Make IIO value formating function globally available to allow IIO drivers
to output values as the core does.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index d0a84fe..a45eb2c 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -470,6 +470,7 @@
 		return 0;
 	}
 }
+EXPORT_SYMBOL_GPL(iio_format_value);
 
 static ssize_t iio_read_channel_info(struct device *dev,
 				     struct device_attribute *attr,