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.com


Signed-off-by: Mark Brown <broonie@kernel.org>