mlxsw: spectrum_acl: Prepare for Spectrum-2 block encoding

In Spectrum the key (and mask) block layout is very straight forward and
every block is 16 bytes aligned.

However, in Spectrum-2 the blocks are not even byte aligned, which makes
it difficult to encode them using current method.

Instead, first encode each block and then encode the block in the
general blocks layout.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>