usb: gadget: mass_storage: set msg_registered after msg registered

BugLink: http://bugs.launchpad.net/bugs/1724783

commit 8e55d303 upstream.

If there is no UDC available, the msg register will fail and this
flag will not be set, but the driver is already added into pending
driver list, then the module removal modprobe -r can not remove
the driver from the pending list.
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/usb/gadget/legacy/mass_storage.c

@@ -210,7 +210,6 @@ static int msg_bind(struct usb_composite_dev *cdev)
 	usb_composite_overwrite_options(cdev, &coverwrite);
 	dev_info(&cdev->gadget->dev,
 		 DRIVER_DESC ", version: " DRIVER_VERSION "\n");
-	set_bit(0, &msg_registered);
 	return 0;
 
 fail_otg_desc:
@@ -257,7 +256,12 @@ MODULE_LICENSE("GPL");
 
 static int __init msg_init(void)
 {
-	return usb_composite_probe(&msg_driver);
+	int ret;
+
+	ret = usb_composite_probe(&msg_driver);
+	set_bit(0, &msg_registered);
+
+	return ret;
 }
 module_init(msg_init);