mlxsw: spectrum_acl: Move mr_ruleset and mr_rule structs

Move the struct to the place where they belong, alongside with the rest
of the MR code.

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>