iio: adc: ad7173: check return value of spi_setup()

iio: adc: ad7173: check return value of spi_setup()

Check the return value of spi_setup() and propagate the error in the
ad7173_probe() function. This is unlikely to happen since virtually
every SPI controller supports SPI_MODE_3, but still always a good idea
to check the return value.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250611-iio-adc-ad7173-check-spi_setup-return-v1-1-4d6f9ef0a2e4@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>