net: dsa: felix: fix incorrect action offsets for VCAP IS2

The port mask width was larger than the actual number of ports, and
therefore, all fields following this one were also shifted by the number
of excess bits. But the driver doesn't use the REW_OP, SMAC_REPLACE_ENA
or ACL_ID bits from the action vector, so the bug was inconsequential.

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