carl9170: fix state downgrade during reset

Don't mark the device as completely dead just yet.
If all goes to plan and carl9170_reboot succeeds
then we can skip the expensive userspace-driven
reinitialization anyway.

And if it doesn't and carl9170_reboot fails,
then carl9170_usb_cancel_urbs will do the
necessary steps.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>