net: Only define skb_mark_napi_id in one spot instead of two

Instead of defining two versions of skb_mark_napi_id I think it is more
readable to just match the format of the sk_mark_napi_id functions and just
wrap the contents of the function instead of defining two versions of the
function.  This way we can save a few lines of code since we only need 2 of
the ifdef/endif but needed 5 for the extra function declaration.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>