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

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