ofproto-dpif: Don't count misses in OpenFlow table stats.

ofproto-dpif: Don't count misses in OpenFlow table stats.

Originally no rule existed for packets that did not match an
OpenFlow flow and therefore every packet with a rule could be
counted as a hit. However, newer versions of OVS have hidden
miss rules so this is no longer true. To return the correct
table stats, this subtracts packets that hit the miss rule
from the total and removes the separate counter.

Reported-by: love you <thunder.love07@gmail.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>