phy: phy-can-transceiver: Skip warning if no "max-bitrate"

According to the DT bindings, the "max-bitrate" property is optional.
However, when it is not present, a warning is printed.
Fix this by adding a missing check for -EINVAL.

Fixes: a4a86d273ff1b6f7 ("phy: phy-can-transceiver: Add support for generic CAN transceiver driver")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/88e15[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/phy/phy-can-transceiver.c

···
 	struct gpio_desc *standby_gpio;
 	struct gpio_desc *enable_gpio;
 	u32 max_bitrate = 0;
+	int err;
 
 	can_transceiver_phy = devm_kzalloc(dev, sizeof(struct can_transceiver_phy), GFP_KERNEL);
 	if (!can_transceiver_phy)
···
 		return PTR_ERR(phy);
 	}
 
-	device_property_read_u32(dev, "max-bitrate", &max_bitrate);
-	if (!max_bitrate)
+	err = device_property_read_u32(dev, "max-bitrate", &max_bitrate);
+	if ((err != -EINVAL) && !max_bitrate)
 		dev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit\n");
 	phy->attrs.max_link_rate = max_bitrate;