Ever since this driver was merged the following code was included:

if (skb->len < MISR)
	skb->len = MISR;

MISR is defined to 0x3C which is also equivalent to ETH_ZLEN, but use
ETH_ZLEN directly which is exactly what we want to be checking for.
Reported-by: NMarc Volovic <marcv@ezchip.com>
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>