[PATCH] sky2: remove cloned/pskb_expand_head check

The code to handle cloned skb overwriting is unnecessary in the
sky2 driver and is buggy. The bug is that pskb_expand_head can change the
skb but the driver has already mapped in the header.

Since the sky2 hardware doesn't need to overwrite memory, the buggy
code can just be removed; it was mistakenly copied from the tg3
driver.

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