r6040: change the default waiting time

This patch changes the default waiting time of a packet, which
along with our previous r6040_rx path, was causing huge delays
with another host (160 to 230 ms).

Signed-off-by: Florian Fainelli <florian.fainelli@telecomint.eu>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>