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/host/ehci-msm.c b/drivers/usb/host/ehci-msm.c
index c7615fb..6b4ffb5 100644
--- a/drivers/usb/host/ehci-msm.c
+++ b/drivers/usb/host/ehci-msm.c
@@ -146,7 +146,7 @@
 	 * management.
 	 */
 	phy = usb_get_phy(USB_PHY_TYPE_USB2);
-	if (!phy) {
+	if (IS_ERR_OR_NULL(phy)) {
 		dev_err(&pdev->dev, "unable to find transceiver\n");
 		ret = -ENODEV;
 		goto unmap;