drm/bridge/synopsys: dsi: Use devm_platform_ioremap_resource() in __dw_mipi_dsi_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>
Reviewed-by: Yannick Fertré <yannick.fertre@st.com>
Tested-by: Yannick Fertré <yannick.fertre@st.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e0d7b7d7-3e89-8b3f-04ed-0b14806e66f7@web.de