phy: bcm-ns-usb2: improve printing ref clk errors

Improve message & use dev_err_probe() helper which prints actual error
(helpful for debugging) and deals with -EPROBE_DEFER.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20211123221521.25323-1-zajec5@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/broadcom/phy-bcm-ns-usb2.c

@@ -132,7 +132,7 @@ static int bcm_ns_usb2_probe(struct platform_device *pdev)
 
 	usb2->ref_clk = devm_clk_get(dev, "phy-ref-clk");
 	if (IS_ERR(usb2->ref_clk)) {
-		dev_err(dev, "Clock not defined\n");
+		dev_err_probe(dev, PTR_ERR(usb2->ref_clk), "failed to get ref clk\n");
 		return PTR_ERR(usb2->ref_clk);
 	}