phy: can-transceiver: Re-instate "mux-states" property presence check

On the Renesas Gray Hawk Single development board:

    can-transceiver-phy can-phy0: /can-phy0: failed to get mux-state (0)

"mux-states" is an optional property for CAN transceivers.  However,
mux_get() always prints an error message in case of an error, including
when the property is not present, confusing the user.

Fix this by re-instating the property presence check (this time using
the proper API) in a wrapper around devm_mux_state_get().  When the
multiplexer subsystem gains support for optional muxes, the wrapper can
just be removed.

In addition, propagate all real errors upstream, instead of ignoring
them.

Fixes: d02dfd4 ("phy: can-transceiver: Drop unnecessary "mux-states" property presence check")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/3d7e0d723908284e8cf06ad1f7950c03173178f3.1742483710.git.geert+renesas@glider.be
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: geertu

drivers/phy/phy-can-transceiver.c

@@ -93,6 +93,16 @@ static const struct of_device_id can_transceiver_phy_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
+/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
+static inline struct mux_state *
+devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+{
+	if (!of_property_present(dev->of_node, "mux-states"))
+		return NULL;
+
+	return devm_mux_state_get(dev, mux_name);
+}
+
 static int can_transceiver_phy_probe(struct platform_device *pdev)
 {
 	struct phy_provider *phy_provider;
@@ -114,13 +124,11 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
 	drvdata = match->data;
 
-	mux_state = devm_mux_state_get(dev, NULL);
-	if (IS_ERR(mux_state)) {
-		if (PTR_ERR(mux_state) == -EPROBE_DEFER)
-			return PTR_ERR(mux_state);
-	} else {
-		can_transceiver_phy->mux_state = mux_state;
-	}
+	mux_state = devm_mux_state_get_optional(dev, NULL);
+	if (IS_ERR(mux_state))
+		return PTR_ERR(mux_state);
+
+	can_transceiver_phy->mux_state = mux_state;
 
 	phy = devm_phy_create(dev, dev->of_node,
 			      &can_transceiver_phy_ops);