Do not log normal interrupt-urb shutdowns as errors.

The option driver has always been logging any nonzero interrupt-urb
status as an error, including when the urb is killed during normal
operation.

Commit 9096f1fb ("USB: usb_wwan: fix potential NULL-deref at
resume") moved the interrupt urb submission from port probe and release
to open and close, thus potentially increasing the number of these
false-positive error messages dramatically.
Reported-by: NEd Butler <ressy66@ausics.net>
Tested-by: NEd Butler <ressy66@ausics.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: NJohan Hovold <johan@kernel.org>