net: dsa: sja1105: make config table operation structures constant

The per-chip instantiations of struct sja1105_table_ops and struct
sja1105_dynamic_table_ops can be made constant, so do that.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>