ASoC: SOF: mediatek: mt8195: Add mailbox generic callbacks for IPC

Add the .mailbox_{read,write} generic callbacks for SOF IPC and, while
at it, also change the ipc_msg_data callback to use the SOF API
sof_ipc_msg_data() instead of the custom function mt8195_ipc_msg_data().

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220906092727.37324-4-angelogioacchino.delregno@collabora.com


Signed-off-by: Mark Brown <broonie@kernel.org>