mlxsw: core: Push code doing params register/unregister into separate helpers

Extract the code calling params register/unregister driver ops into
separate functions. Call publish/unpublish unconditionally.

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