iio: adc: ad7949: use spi_is_bpw_supported()

Use spi_is_bpw_supported() instead of directly accessing spi->controller
->bits_per_word_mask. bits_per_word_mask may be 0, which implies that
8-bits-per-word is supported. spi_is_bpw_supported() takes this into
account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.

Fixes: 0b2a740 ("iio: adc: ad7949: enable use with non 14/16-bit controllers")
Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://patch.msgid.link/20250611-iio-adc-ad7949-use-spi_is_bpw_supported-v1-1-c4e15bfd326e@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: dlech

drivers/iio/adc/ad7949.c

@@ -308,7 +308,6 @@ static void ad7949_disable_reg(void *reg)
 
 static int ad7949_spi_probe(struct spi_device *spi)
 {
-	u32 spi_ctrl_mask = spi->controller->bits_per_word_mask;
 	struct device *dev = &spi->dev;
 	const struct ad7949_adc_spec *spec;
 	struct ad7949_adc_chip *ad7949_adc;
@@ -337,11 +336,11 @@ static int ad7949_spi_probe(struct spi_device *spi)
 	ad7949_adc->resolution = spec->resolution;
 
 	/* Set SPI bits per word */
-	if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) {
+	if (spi_is_bpw_supported(spi, ad7949_adc->resolution)) {
 		spi->bits_per_word = ad7949_adc->resolution;
-	} else if (spi_ctrl_mask == SPI_BPW_MASK(16)) {
+	} else if (spi_is_bpw_supported(spi, 16)) {
 		spi->bits_per_word = 16;
-	} else if (spi_ctrl_mask == SPI_BPW_MASK(8)) {
+	} else if (spi_is_bpw_supported(spi, 8)) {
 		spi->bits_per_word = 8;
 	} else {
 		dev_err(dev, "unable to find common BPW with spi controller\n");