ASoC: SOF: mediatek: Constify struct mtk_adsp_ipc_ops

'struct mtk_adsp_ipc_ops' is not modified in these drivers.

Constifying this structure moves some data to a read-only section, so
increase overall security.

In order to do it, "struct mtk_adsp_ipc" also needs to be adjusted to this
new const qualifier.

On a x86_64, with allmodconfig:
Before:
======
text data bss dec hex filename
15533 2383 0 17916 45fc sound/soc/sof/mediatek/mt8195/mt8195.o

After:
=====
text data bss dec hex filename
15557 2367 0 17924 4604 sound/soc/sof/mediatek/mt8195/mt8195.o

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://msgid.link/r/a45d6b2b5e[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/linux/firmware/mediatek/mtk-adsp-ipc.h

···
 struct mtk_adsp_ipc {
 	struct mtk_adsp_chan chans[MTK_ADSP_MBOX_NUM];
 	struct device *dev;
-	struct mtk_adsp_ipc_ops *ops;
+	const struct mtk_adsp_ipc_ops *ops;
 	void *private_data;
 };
 

sound/soc/sof/mediatek/mt8186/mt8186.c

···
 	}
 }
 
-static struct mtk_adsp_ipc_ops dsp_ops = {
+static const struct mtk_adsp_ipc_ops dsp_ops = {
 	.handle_reply		= mt8186_dsp_handle_reply,
 	.handle_request		= mt8186_dsp_handle_request,
 };

sound/soc/sof/mediatek/mt8195/mt8195.c

···
 	}
 }
 
-static struct mtk_adsp_ipc_ops dsp_ops = {
+static const struct mtk_adsp_ipc_ops dsp_ops = {
 	.handle_reply		= mt8195_dsp_handle_reply,
 	.handle_request		= mt8195_dsp_handle_request,
 };