ASoC: SOF: imx: make imx8m_dsp_ops static

This was in the SOF tree but lost in upstream contributions.

Fixes: afb93d71 ("ASoC: SOF: imx: Add i.MX8M HW support")
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20200515135958.17511-9-kai.vehmanen@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/imx/imx8m.c

@@ -92,7 +92,7 @@ static void imx8m_dsp_handle_request(struct imx_dsp_ipc *ipc)
 	snd_sof_ipc_msgs_rx(priv->sdev);
 }
 
-struct imx_dsp_ops imx8m_dsp_ops = {
+static struct imx_dsp_ops imx8m_dsp_ops = {
 	.handle_reply		= imx8m_dsp_handle_reply,
 	.handle_request		= imx8m_dsp_handle_request,
 };