xlate: Always recirculate after an MPLS POP to a non-MPLS ethertype.

xlate: Always recirculate after an MPLS POP to a non-MPLS ethertype.

So far we have tried to optimize MPLS POP action not to recirculate
unless later matching actually needs the inner headers.  This made the
code complex and error-prone.  Also the cases where this optimization
would have been useful seem rare, as one would typically want to do
something else with the inner packet than blindly send it to some
output port.

With this change multiple consecutive MPLS POPs do not need
recirculation in between, so even if the blind output case is now
little bit less optimal, the multiple POP case is correspondingly
faster with this change.

Suggested-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>