spi: Constify spi_get_drvdata()'s spi parameter

The "spi" parameter of spi_get_drvdata() can be const.
dev_get_drvdata() has been taking a const pointer since commit
7d1d8999b4 ("i2c: Constify i2c_get_clientdata's parameter").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/0f1700ade27a8f3935d04480ff7bef8a887331eb.1678704562.git.geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/spi/spi.h

@@ -261,7 +261,7 @@ static inline void spi_set_drvdata(struct spi_device *spi, void *data)
 	dev_set_drvdata(&spi->dev, data);
 }
 
-static inline void *spi_get_drvdata(struct spi_device *spi)
+static inline void *spi_get_drvdata(const struct spi_device *spi)
 {
 	return dev_get_drvdata(&spi->dev);
 }