soc: mediatek: cmdq: Add cmdq_pkt_eoc() helper function

cmdq_pkt_eoc() append eoc command to CMDQ packet. eoc command
would ask GCE to generate IRQ. It's usually appended to the end
of packet to notify all command in the packet is done.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Link: https://lore.kernel.org/r/20240222154120.16959-6-chunkuang.hu@kernel.org


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>