usb: gadget: tegra-xudc: Fix idle suspend/resume

When the XUDC device is idle (i.e. powergated), care must be taken not
to access any registers because that would lead to a crash.

Move the call to tegra_xudc_device_mode_off() into the same conditional
as the tegra_xudc_powergate() call to make sure we only force device
mode off if the XUDC is actually powered up.

Fixes: 49db4272 ("usb: gadget: Add UDC driver for tegra XUSB device mode controller")
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/udc/tegra-xudc.c

@@ -3840,11 +3840,11 @@ static int __maybe_unused tegra_xudc_suspend(struct device *dev)
 
 	flush_work(&xudc->usb_role_sw_work);
 
-	/* Forcibly disconnect before powergating. */
-	tegra_xudc_device_mode_off(xudc);
-
-	if (!pm_runtime_status_suspended(dev))
+	if (!pm_runtime_status_suspended(dev)) {
+		/* Forcibly disconnect before powergating. */
+		tegra_xudc_device_mode_off(xudc);
 		tegra_xudc_powergate(xudc);
+	}
 
 	pm_runtime_disable(dev);