[SCSI] fcoe: fix kfree(skb)

Use kfree_skb instead of kfree for struct sk_buff pointers.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>