remoteproc: qcom: Add shutdown-ack irq

Add shutdown-ack irq handling required for sysmon shutdown for
Q6V5 MSS on SDM845/MSM8996 and for WCSS Q6V5 on QCS404 SoC.

Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
[bjorn: Revert back to qcom_add_sysmon_subdev returning a sysmon object]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
index c86dc40..07d1cc5 100644
--- a/drivers/remoteproc/qcom_q6v5_mss.c
+++ b/drivers/remoteproc/qcom_q6v5_mss.c
@@ -1341,6 +1341,10 @@ static int q6v5_probe(struct platform_device *pdev)
 	qcom_add_smd_subdev(rproc, &qproc->smd_subdev);
 	qcom_add_ssr_subdev(rproc, &qproc->ssr_subdev, "mpss");
 	qproc->sysmon = qcom_add_sysmon_subdev(rproc, "modem", 0x12);
+	if (IS_ERR(qproc->sysmon)) {
+		ret = PTR_ERR(qproc->sysmon);
+		goto free_rproc;
+	}
 
 	ret = rproc_add(rproc);
 	if (ret)