[PATCH] sky2: use netif_tx_lock instead of LLTX

Use the netdevice transmit lock via netif_tx_lock rather than putting
lock in device specific code and using lockless transmit.  The code is
cleaner using netif_tx_lock, and the performance is same.

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