USB: serial: opticon: fix control-message timeouts

The driver was issuing synchronous uninterruptible control requests
without using a timeout. This could lead to the driver hanging
on open() or tiocmset() due to a malfunctioning (or malicious) device
until the device is physically disconnected.

The USB upper limit of five seconds per request should be more than
enough.

Fixes: 309a0579

 ("USB: opticon: add rts and cts support")
Cc: stable <stable@vger.kernel.org>     # 2.6.39
Cc: Martin Jansen <martin.jansen@opticon.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>