spi: lantiq-ssc: Use devm_platform_ioremap_resource() in lantiq_ssc_probe()

Simplify this function implementation by using a known wrapper function.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Link: https://lore.kernel.org/r/230495a7-b754-bc6a-05e0-059a6b6c643d@web.de


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