Input: iforce - use usb_kill_urb instead of usb_unlink_urb

Using usb_unlink_urb can cause iforce_open to fail when called
soon after iforce_release. Also updated my email address and
replaced calls to printk() by dbg(), warn(), info(), err()...

Signed-off-by: Johann Deneux <johann.deneux@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>