rpmsg: qcom_smd: Fix fallback to qcom,ipc parse

mbox_request_channel() returning value was changed in case of error.
It uses returning value of of_parse_phandle_with_args().
It is returning with -ENOENT instead of -ENODEV when no mboxes property
exists.

Fixes: 24fdd50 ("mailbox: use error ret code of of_parse_phandle_with_args()")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Tested-by: Stephan Gerhold <stephan.gerhold@linaro.org> # msm8939
Signed-off-by: Barnabás Czémán <barnabas.czeman@mainlining.org>
Link: https://lore.kernel.org/r/20250725-fix-qcom-smd-v2-1-e4e43613f874@mainlining.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: barni2000

drivers/rpmsg/qcom_smd.c

@@ -1368,7 +1368,7 @@ static int qcom_smd_parse_edge(struct device *dev,
 	edge->mbox_client.knows_txdone = true;
 	edge->mbox_chan = mbox_request_channel(&edge->mbox_client, 0);
 	if (IS_ERR(edge->mbox_chan)) {
-		if (PTR_ERR(edge->mbox_chan) != -ENODEV) {
+		if (PTR_ERR(edge->mbox_chan) != -ENOENT) {
 			ret = dev_err_probe(dev, PTR_ERR(edge->mbox_chan),
 					    "failed to acquire IPC mailbox\n");
 			goto put_node;