spi: pxa2xx-pci: Move dma_burst_size assignment to ->setup()

Instead of using conditional, move dma_burst_size to the corresponding
->setup() function.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220225172350.69797-5-andriy.shevchenko@linux.intel.com


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