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

Move max_clk_rate to the corresponding ->setup() function to unify
with the rest.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220225172350.69797-6-andriy.shevchenko@linux.intel.com


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