The mentioned cache was introduced to reduce the number of skb
allocation in atomic context, but the required complexity is
excessive.

This change remove the mentioned cache.
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>