staging: hikey9xx: Fix incorrect assignment

In hi3670_phy_probe(), when reading property tx-vboost-lvl fails, its
default value is assigned to priv->eye_diagram_param, rather than to
priv->tx_vboost_lvl. Fix this.

Fixes: 8971a3b8 ("staging: hikey9xx: add USB physical layer for Kirin 3670")
Addresses-Coverity: CID 1497107: Incorrect expression (COPY_PASTE_ERROR)
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Link: https://lore.kernel.org/r/20200921212146.34662-1-alex.dewar90@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/hikey9xx/phy-hi3670-usb3.c

@@ -640,7 +640,7 @@ static int hi3670_phy_probe(struct platform_device *pdev)
 
 	if (of_property_read_u32(dev->of_node, "hisilicon,tx-vboost-lvl",
 				 &priv->tx_vboost_lvl))
-		priv->eye_diagram_param = KIRIN970_USB_DEFAULT_PHY_VBOOST;
+		priv->tx_vboost_lvl = KIRIN970_USB_DEFAULT_PHY_VBOOST;
 
 	phy = devm_phy_create(dev, NULL, &hi3670_phy_ops);
 	if (IS_ERR(phy))