Add a counter that counts the number of masks cache hits, and
export it through the megaflow netlink statistics.
Reviewed-by: NPaolo Abeni <pabeni@redhat.com>
Reviewed-by: NTonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: NEelco Chaudron <echaudro@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>