[IrDA]: f-timer reloading when sending rejected frames.

Jean II was right: you have to re-charge the final timer when
resending rejected frames. Otherwise it triggers at a wrong time and
can break the currently running communication. Reproducible under
rt-preempt.

Signed-off-by: G. Liakhovetski <gl@dsa-ac.de>
Signed-off-by: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>