spi: pxa2xx: Make num_chipselect 8-bit in the struct pxa2xx_spi_controller

There is no use for whole 16-bit for the number of chip select pins.
Drop it to 8 bits.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://msgid.link/r/20240307195056.4059864-3-andriy.shevchenko@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/spi/pxa2xx.rst

@@ -24,7 +24,7 @@ arch/.../mach-*/board-*.c as a "platform device". The host controller configurat
 is passed to the driver via a table found in include/linux/spi/pxa2xx_spi.h::
 
   struct pxa2xx_spi_controller {
-	u16 num_chipselect;
+	u8 num_chipselect;
 	u8 enable_dma;
 	...
   };

include/linux/spi/pxa2xx_spi.h

@@ -17,7 +17,7 @@ struct dma_chan;
  * (resides in device.platform_data).
  */
 struct pxa2xx_spi_controller {
-	u16 num_chipselect;
+	u8 num_chipselect;
 	u8 enable_dma;
 	u8 dma_burst_size;
 	bool is_target;