ASoC: ssm2518: drop support for platform data

There are currently no users of this driver's platform data in the
mainline kernel, so let's drop it.

Newer devices should use DT, ACPI, or static software properties to
describe the hardware.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20220920025804.1788667-1-dmitry.torokhov@gmail.com


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