usb: xhci-rcar: deregister before deactivating clock

During the execution of xhci_deregister xHCI registers are accessed. If
the clock is already deactivated when xhci_deregister is called this can
lead to undefined behavior. Change the order to deregister the device
before deactivating the clock.

Signed-off-by: Matthias Blankertz <matthias.blankertz@cetitec.com>
diff --git a/drivers/usb/host/xhci-rcar.c b/drivers/usb/host/xhci-rcar.c
index a837afc..f2e91ef 100644
--- a/drivers/usb/host/xhci-rcar.c
+++ b/drivers/usb/host/xhci-rcar.c
@@ -117,12 +117,15 @@
 
 static int xhci_rcar_deregister(struct udevice *dev)
 {
+	int ret;
 	struct rcar_xhci_platdata *plat = dev_get_platdata(dev);
 
+	ret = xhci_deregister(dev);
+
 	clk_disable(&plat->clk);
 	clk_free(&plat->clk);
 
-	return xhci_deregister(dev);
+	return ret;
 }
 
 static int xhci_rcar_ofdata_to_platdata(struct udevice *dev)