usb: dwc2: move usb_disabled() call to host driver only

Since platform.c will get built for both Host and Gadget, if we leave the
usb_disabled() call in platform.c, it results in the following build error
when (!USB && USB_GADGET) condition is met.

ERROR: "usb_disabled" [drivers/usb/dwc2/dwc2_platform.ko] undefined!

Since usb_disabled() is mostly used to disable USB host functionality, move
the call the host portion for the DWC2 driver.
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/hcd.c

@@ -2846,6 +2846,9 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq,
 	int i, num_channels;
 	int retval;
 
+	if (usb_disabled())
+		return -ENODEV;
+
 	dev_dbg(hsotg->dev, "DWC OTG HCD INIT\n");
 
 	/* Detect config values from hardware */

drivers/usb/dwc2/platform.c

@@ -157,9 +157,6 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	int retval;
 	int irq;
 
-	if (usb_disabled())
-		return -ENODEV;
-
 	match = of_match_device(dwc2_of_match_table, &dev->dev);
 	if (match && match->data) {
 		params = match->data;