ofproto-dpif: Fake-up OFPP_NONE input bundle for mirroring and normal.

ofproto-dpif: Fake-up OFPP_NONE input bundle for mirroring and normal.

Both mirroring and "normal" processing make use of the input bundle to
perform various sanity checks.  Controller-generated traffic typically
uses an ingress port of OFPP_NONE, which doesn't have a corresponding
input bundle.  This commit fakes one up well enough that mirroring and
"normal" processing succeed.

We looked at creating an actual bundle based on the "real" OFPP_NONE.
This was even uglier, since there were even more special-cases that
needed to be handled, including having to hide it from port queries.

Reported-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: Justin Pettit <jpettit@nicira.com>