spi: mpc5xxx-psc: use devm_clk_get_enabled() for core clock

Use devm_clk_get_enabled() to simplify the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230306183115.87314-4-andriy.shevchenko@linux.intel.com


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