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 <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/industrialio-core.c

···
 		return 0;
 	}
 }
+EXPORT_SYMBOL_GPL(iio_format_value);
 
 static ssize_t iio_read_channel_info(struct device *dev,
 				     struct device_attribute *attr,

include/linux/iio/iio.h

···
 }
 #endif
 
+ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals);
+
 int iio_str_to_fixpoint(const char *str, int fract_mult, int *integer,
 	int *fract);