Add a new rate control algorithm based on a PID controller. It samples the
percentage of failed frames over time, feeds the result into the controller and
uses its output to control the TX rate.
Signed-off-by: NMattias Nissler <mattias.nissler@gmx.de>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>