skbuff: remove unused dev_consume_skb macro definition

dev_consume_skb and kfree_skb_clean have no users and in the case of
kfree_skb_clean could cause potential build issues since I cannot find
where it is defined.  Based on the patch in which it was introduced it
appears to have been a bit of leftover code from an earlier version of the
patch in which kfree_skb_clean was dropped in favor of consume_skb.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>