URB is the only resource that is not managed, and thus is destroyed too early,
before we unregister input device and stop URB in pxrc_close(). To fix it let's
install custom devm handler to free the URB at the right time in devm unwind
sequence.
Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Tested-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>