sky2: restore workarounds for lost interrupts

This patch restores a couple of workarounds from 2.6.16:
 * restart transmit moderation timer in case it expires during IRQ routine
 * default to having 10 HZ watchdog timer.
At this point it more important not to hang than to worry about the
power cost.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>