USB: serial: mos7720: fix mos_parport refcount imbalance on error path

commit 2908b076f5198d231de62713cb2b633a3a4b95ac upstream.

The write_parport_reg_nonblock() helper takes a reference to the struct
mos_parport, but failed to release it in a couple of error paths after
allocation failures, leading to a memory leak.

Johan said that move the kref_get() and mos_parport assignment to the
end of urbtrack initialisation is a better way, so move it. and
mos_parport do not used until urbtrack initialisation.

Signed-off-by: Lin Yi <teroincn@163.com>
Fixes: b69578df ("USB: usbserial: mos7720: add support for parallel port on moschip 7715")
Cc: stable <stable@vger.kernel.org>     # 2.6.35
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>