iio:dac:ad5686: Add support for AD5685R

This driver acctually supports the AD5685R device and NOT the AD5685, which
does not exist.  Maintain old id entry in case we have devicetrees
out there which are using the wrong name.

More information can be found in the datasheet:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5686_5684.pdf

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad5686.c

@@ -88,7 +88,7 @@ struct ad5686_state {
 
 enum ad5686_supported_device_ids {
 	ID_AD5684,
-	ID_AD5685,
+	ID_AD5685R,
 	ID_AD5686,
 };
 static int ad5686_spi_write(struct ad5686_state *st,
@@ -303,7 +303,7 @@ static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
 		.num_channels = 4,
 		.int_vref_mv = 2500,
 	},
-	[ID_AD5685] = {
+	[ID_AD5685R] = {
 		.channels = ad5685r_channels,
 		.int_vref_mv = 2500,
 		.num_channels = 4,
@@ -392,7 +392,8 @@ static int ad5686_remove(struct spi_device *spi)
 
 static const struct spi_device_id ad5686_id[] = {
 	{"ad5684", ID_AD5684},
-	{"ad5685", ID_AD5685},
+	{"ad5685", ID_AD5685R}, /* Does not exist */
+	{"ad5685r", ID_AD5685R},
 	{"ad5686", ID_AD5686},
 	{}
 };