usb: dwc3: xilinx: fix uninitialized return value

A previous patch to skip part of the initialization when a USB3 PHY was
not present could result in the return value being uninitialized in that
case, causing spurious probe failures. Initialize ret to 0 to avoid this.

Fixes: 9678f336 ("usb: dwc3: xilinx: Skip resets and USB3 register settings for USB2.0 mode")
Cc: <stable@vger.kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Link: https://lore.kernel.org/r/20220127221500.177021-1-robert.hancock@calian.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/dwc3-xilinx.c

@@ -99,7 +99,7 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
 	struct device		*dev = priv_data->dev;
 	struct reset_control	*crst, *hibrst, *apbrst;
 	struct phy		*usb3_phy;
-	int			ret;
+	int			ret = 0;
 	u32			reg;
 
 	usb3_phy = devm_phy_optional_get(dev, "usb3-phy");