spi: mpc5xxx-psc: Return immediately if IRQ resource is unavailable

Return immediately if IRQ resource is unavailable. This will also
propagate the correct error code in such cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230306183115.87314-3-andriy.shevchenko@linux.intel.com


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