spi: pxa2xx: Switch to use SPI core GPIO (legacy) CS handling

SPI core has been already providing the GPIO CS handling. Use it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210517140351.901-4-andriy.shevchenko@linux.intel.com


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