spi: mpc52xx: Replace of_gpio_count() by gpiod_count()

As a preparation to unexport of_gpio_named_count(), convert the
driver to use gpiod_count() instead.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220914153333.37701-1-andriy.shevchenko@linux.intel.com


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