spi: mediatek: Use devm_platform_ioremap_resource() in mtk_spi_slave_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/225b76ca-a367-4bef-d8ce-42c7af9242a5@web.de


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