drm/stm: dsi: Use devm_platform_ioremap_resource()

Convert platform_get_resource(),devm_ioremap_resource() to a single call
to devm_platform_ioremap_resource(), as this is exactly what this function
does.

Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230421083402.21364-1-yang.lee@linux.alibaba.com