Remove MAX_ACTIONS (which was 16) as a limit on the number of actions in a flow table...

Remove MAX_ACTIONS (which was 16) as a limit on the number of actions in a flow table entry.

Now the number of actions is limited, as a practical matter, to the size
of the buffer that the kernel provides for Netlink dumps, which is usually
4096 bytes.  A flow statistics entry must fit in a single one of these
buffers.  Actions are 8 bytes each, so this is about 500 actions
considering overhead.