[PATCH] sky2: force early transmit status

Need to force a transmit coalesce timer restart after processing
transmit packets. Otherwise, can get transmit status after last
update and chip doesn't send the next one.

Can go with the chip defaults for coalescing timers, except for
Tx timer which needs to be bigger.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>