usb: gadget: Fix setting self-powered state on suspend

cdev->config might be NULL, so check it before dereferencing.

CC: stable <stable@kernel.org>
Fixes: 40e89ff ("usb: gadget: Set self-powered based on MaxPower and bmAttributes")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250220120314.3614330-1-m.szyprowski@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: mszyprow

drivers/usb/gadget/composite.c

@@ -2616,7 +2616,8 @@ void composite_suspend(struct usb_gadget *gadget)
 
 	cdev->suspended = 1;
 
-	if (cdev->config->bmAttributes & USB_CONFIG_ATT_SELFPOWER)
+	if (cdev->config &&
+	    cdev->config->bmAttributes & USB_CONFIG_ATT_SELFPOWER)
 		usb_gadget_set_selfpowered(gadget);
 
 	usb_gadget_vbus_draw(gadget, 2);