iio:light:tsl2563: Add DT support

Add Device Tree support for the TSL2563 driver,
document the binding and add AMS-TAOS Inc. to the
list of vendor prefixes.

Signed-off-by: Sebastian Reichel <sre@debian.org>
Acked-by: Kumar Gala <galak@codeaurora.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/light/tsl2563.c

@@ -714,6 +714,7 @@ static int tsl2563_probe(struct i2c_client *client,
 	struct iio_dev *indio_dev;
 	struct tsl2563_chip *chip;
 	struct tsl2563_platform_data *pdata = client->dev.platform_data;
+	struct device_node *np = client->dev.of_node;
 	int err = 0;
 	u8 id = 0;
 
@@ -750,6 +751,9 @@ static int tsl2563_probe(struct i2c_client *client,
 
 	if (pdata)
 		chip->cover_comp_gain = pdata->cover_comp_gain;
+	else if (np)
+		of_property_read_u32(np, "amstaos,cover-comp-gain",
+				     &chip->cover_comp_gain);
 	else
 		chip->cover_comp_gain = 1;