High order GFP_KERNEL allocations can stress the host badly.

Use modern kvmalloc_array()/kvfree() instead of custom
allocations.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>