spi: Constify spi parameters of chip select APIs

The "spi" parameters of spi_get_chipselect() and spi_get_csgpiod() can
be const.

Fixes: 303feb3c ("spi: Add APIs in spi core to set/get spi->chip_select and spi->cs_gpiod")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/b112de79e7a1e9095a3b6ff22b639f39e39d7748.1678704562.git.geert+renesas@glider.beSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/spi/spi.h

@@ -266,7 +266,7 @@ static inline void *spi_get_drvdata(const struct spi_device *spi)
 	return dev_get_drvdata(&spi->dev);
 }
 
-static inline u8 spi_get_chipselect(struct spi_device *spi, u8 idx)
+static inline u8 spi_get_chipselect(const struct spi_device *spi, u8 idx)
 {
 	return spi->chip_select;
 }
@@ -276,7 +276,7 @@ static inline void spi_set_chipselect(struct spi_device *spi, u8 idx, u8 chipsel
 	spi->chip_select = chipselect;
 }
 
-static inline struct gpio_desc *spi_get_csgpiod(struct spi_device *spi, u8 idx)
+static inline struct gpio_desc *spi_get_csgpiod(const struct spi_device *spi, u8 idx)
 {
 	return spi->cs_gpiod;
 }