drm/mediatek: mtk_hdmi: Improve mtk_hdmi_get_all_clk() flexibility

drm/mediatek: mtk_hdmi: Improve mtk_hdmi_get_all_clk() flexibility

In preparation for splitting common bits of this driver and for
introducing a new version of the MediaTek HDMI Encoder IP, improve
the flexibility	of function mtk_hdmi_get_all_clk() by adding a
pointer to the clock names array and size of it to its parameters.

Also change the array of struct clock pointers in the mtk_hdmi
structure to be dynamically allocated, and allocate it in probe.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20251023-mediatek-drm-hdmi-v2-v11-2-7873ec4a1edf@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>