spi: sc18is602: Switch to generic firmware properties and drop of_match_ptr()

This enables using the driver with other firmware types such as ACPI
via PRP0001.

Also part of a general attempt to move drivers over to generic properties
to avoid opportunities for cut and paste.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20241114205051.3747458-1-andriy.shevchenko@linux.intel.com


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