usb: ehci-hcd: Fix crash when no ops are provided to ehci_register()

This commit fixes crash on BananaPi (and possibly others)
casued by 3f9f8a5b83f8aec40c9f4ee496046a695e333c45.

Crash reason:
When no ops were passed to ehci_register(), USB host driver caused
NULL pointer dereference.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>

drivers/usb/host/ehci-hcd.c

@@ -1615,8 +1615,8 @@ int ehci_register(struct udevice *dev, struct ehci_hccr *hccr,
 	if (ret)
 		goto err;
 
-	if (ops->init_after_reset) {
-		ret = ops->init_after_reset(ctrl);
+	if (ctrl->ops.init_after_reset) {
+		ret = ctrl->ops.init_after_reset(ctrl);
 		if (ret)
 			goto err;
 	}