iio: dac: ad5755: make use of of_device_id table

Store pointers to chip info (struct ad5755_chip_info) in driver match
data, instead of enum, so every value will be != 0, populate the
of_device_id table and use it in driver.  Even though it is one change,
it gives multiple benefits:
1. Allows to use spi_get_device_match_data() dropping local 'type'
   variable.
2. Makes both ID tables usable, so kernel can match via any of these
   methods.
3. Code is more obvious as both tables are properly filled.
4. Fixes W=1 warning:
   ad5755.c:866:34: error: unused variable 'ad5755_of_match' [-Werror,-Wunused-const-variable]

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240413154511.52576-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dac/ad5755.c

@@ -809,7 +809,6 @@ static struct ad5755_platform_data *ad5755_parse_fw(struct device *dev)
 
 static int ad5755_probe(struct spi_device *spi)
 {
-	enum ad5755_type type = spi_get_device_id(spi)->driver_data;
 	const struct ad5755_platform_data *pdata;
 	struct iio_dev *indio_dev;
 	struct ad5755_state *st;
@@ -824,7 +823,7 @@ static int ad5755_probe(struct spi_device *spi)
 	st = iio_priv(indio_dev);
 	spi_set_drvdata(spi, indio_dev);
 
-	st->chip_info = &ad5755_chip_info_tbl[type];
+	st->chip_info = spi_get_device_match_data(spi);
 	st->spi = spi;
 	st->pwr_down = 0xf;
 
@@ -854,21 +853,21 @@ static int ad5755_probe(struct spi_device *spi)
 }
 
 static const struct spi_device_id ad5755_id[] = {
-	{ "ad5755", ID_AD5755 },
-	{ "ad5755-1", ID_AD5755 },
-	{ "ad5757", ID_AD5757 },
-	{ "ad5735", ID_AD5735 },
-	{ "ad5737", ID_AD5737 },
+	{ "ad5755", (kernel_ulong_t)&ad5755_chip_info_tbl[ID_AD5755] },
+	{ "ad5755-1", (kernel_ulong_t)&ad5755_chip_info_tbl[ID_AD5755] },
+	{ "ad5757", (kernel_ulong_t)&ad5755_chip_info_tbl[ID_AD5757] },
+	{ "ad5735", (kernel_ulong_t)&ad5755_chip_info_tbl[ID_AD5735] },
+	{ "ad5737", (kernel_ulong_t)&ad5755_chip_info_tbl[ID_AD5737] },
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad5755_id);
 
 static const struct of_device_id ad5755_of_match[] = {
-	{ .compatible = "adi,ad5755" },
-	{ .compatible = "adi,ad5755-1" },
-	{ .compatible = "adi,ad5757" },
-	{ .compatible = "adi,ad5735" },
-	{ .compatible = "adi,ad5737" },
+	{ .compatible = "adi,ad5755", &ad5755_chip_info_tbl[ID_AD5755] },
+	{ .compatible = "adi,ad5755-1", &ad5755_chip_info_tbl[ID_AD5755] },
+	{ .compatible = "adi,ad5757", &ad5755_chip_info_tbl[ID_AD5757] },
+	{ .compatible = "adi,ad5735", &ad5755_chip_info_tbl[ID_AD5735] },
+	{ .compatible = "adi,ad5737", &ad5755_chip_info_tbl[ID_AD5737] },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ad5755_of_match);
@@ -876,6 +875,7 @@ MODULE_DEVICE_TABLE(of, ad5755_of_match);
 static struct spi_driver ad5755_driver = {
 	.driver = {
 		.name = "ad5755",
+		.of_match_table = ad5755_of_match,
 	},
 	.probe = ad5755_probe,
 	.id_table = ad5755_id,