drm/mediatek: mtk_hdmi: Remove ifdef for CONFIG_PM_SLEEP

drm/mediatek: mtk_hdmi: Remove ifdef for CONFIG_PM_SLEEP

Since the SIMPLE_DEV_PM_OPS macro and the pm pointer are anyway
defined when CONFIG_PM_SLEEP is not set, remove the ifdef for it
and indicate that the mtk_hdmi_{remove,suspend} functions may be
unused (as they are, in case PM support is not built-in).

While at it, to improve readability, also compress the
SIMPLE_DEV_PM_OPS declaration as it even fits in less
than 80 columns.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20250217154836.108895-31-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>