usb: phy: fix return value check of usb_get_phy

usb_get_phy will return -ENODEV if it's not able to find the phy. Hence
fixed all the callers of usb_get_phy to check for this error condition
instead of relying on a non-zero value as success condition.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c
index 2813490..5fdb9da 100644
--- a/drivers/usb/musb/omap2430.c
+++ b/drivers/usb/musb/omap2430.c
@@ -320,7 +320,7 @@
 	 * which needs a driver, drivers aren't always needed.
 	 */
 	musb->xceiv = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
-	if (!musb->xceiv) {
+	if (IS_ERR_OR_NULL(musb->xceiv)) {
 		pr_err("HS USB OTG: no transceiver configured\n");
 		return -ENODEV;
 	}