pmdomain: mediatek: Use devm_platform_ioremap_resource() in init_scp()

A wrapper function is available since the commit 7945f929
("drivers: provide devm_platform_ioremap_resource()").

* Thus reuse existing functionality instead of keeping duplicate source code.

* Delete a local variable which became unnecessary with this refactoring.

This issue was transformed by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/6e397bf2-1d45-434f-8619-58a737a138e3@web.de


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>