ASoC: SOF: mediatek: remove error checks on NULL ipc

mtk_adsp_ipc_get_data() can return NULL, but the value is not checked
before being used, leading to static analysis warnings.

sound/soc/sof/mediatek/mt8195/mt8195.c:90:32: error: dereference of
NULL ‘0’ [CWE-476] [-Werror=analyzer-null-dereference]

   90 |         spin_lock_irqsave(&priv->sdev->ipc_lock, flags);
      |                            ~~~~^~~~~~

It appears this is not really a possible problem, so remove those checks.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Yaochun Hung <yc.hung@mediatek.com>
Link: https://lore.kernel.org/r/20230731213748.440285-6-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

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

@@ -46,17 +46,11 @@ struct mtk_adsp_ipc {
 
 static inline void mtk_adsp_ipc_set_data(struct mtk_adsp_ipc *ipc, void *data)
 {
-	if (!ipc)
-		return;
-
 	ipc->private_data = data;
 }
 
 static inline void *mtk_adsp_ipc_get_data(struct mtk_adsp_ipc *ipc)
 {
-	if (!ipc)
-		return NULL;
-
 	return ipc->private_data;
 }