tc: Limit the max action number to 16

tc: Limit the max action number to 16

Currently, ovs supports to offload max TCA_ACT_MAX_PRIO(32) actions.
But net sched api has a limit of 4K message size which is not enough
for 32 actions when echo flag is set.

After a lot of testing, we find that 16 actions is a reasonable number.
So in this commit, we introduced a new define to limit the max actions.

Fixes: 0c70132cd288("tc: Make the actions order consistent")
Signed-off-by: Chris Mi <chrism@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>