datapath: reorder action netlink attribute definition for upstreaming

Keeping the order of netlink attribute definition in the order of
upstreaming is the best way to keep all released user space program
forward compatible with upstreamed kernel modules.

Adjust action netlink attribute order to match with the current
upstreaming plan.

Recirc and hash actions are introduced in branch 2.3, which will be
fixed by the patch. The MPLS actions have been released since
branch-2.1 but there is no kernel implementation of them prior to
branch 2.3. Thus the ordering change should not affect them.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>