usb: dwc3: host: remove dead code in dwc3_host_get_irq()

According to the description of platform_get_irq()
 * Return: non-zero IRQ number on success,
 			negative error number on failure.
and the code, platform_get_irq() will return -EINVAL
instead of IRQ0.

So platform_get_irq() no longer returns 0, there is no
need to check whether the return value is 0.

Found by Smatch:
drivers/usb/dwc3/host.c:60 dwc3_host_get_irq()
	warn: platform_get_irq() does not return zero
Signed-off-by: Mingxuan Xiang <mx_xiang@hust.edu.cn>
Reviewed-by: Dan Carpenter <error27@gmail.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230324060934.1686859-1-mx_xiang@hust.edu.cnSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/host.c

@@ -52,13 +52,8 @@ static int dwc3_host_get_irq(struct dwc3 *dwc)
 		goto out;
 
 	irq = platform_get_irq(dwc3_pdev, 0);
-	if (irq > 0) {
+	if (irq > 0)
 		dwc3_host_fill_xhci_irq_res(dwc, irq, NULL);
-		goto out;
-	}
-
-	if (!irq)
-		irq = -EINVAL;
 
 out:
 	return irq;