commit 75dd211e upstream.

Do not submit the interrupt URB until after the parport has been
successfully registered to avoid another use-after-free in the
completion handler when accessing the freed parport private data in case
of a racing completion.

Fixes: b69578df ("USB: usbserial: mos7720: add support for parallel
port on moschip 7715")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>