mlxsw: spectrum: push cls_flower and cls_matchall setup_tc processing into separate functions

Let mlxsw_sp_setup_tc be a splitter for specific setup_tc types and push
out cls_flower and cls_matchall specific codes into separate functions.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>