classifier: Retire partitions.

classifier: Retire partitions.

Classifier partitions allowed skipping subtables when if was known
from the flow's metadata field that the subtable cannot possibly
match.  This functionality was later implemented in a more general
fashion by staged lookup, where the first stage also covers the
metadata field, among the rest of the non-packet fields in the struct
flow.  While in theory skipping a subtable on the basis of the
metadata field alone could produce more effective wildcards, on the
basis of our testsuite coverage it does not seem to be the case, as
removing the partitioning feature did not result in any test failures.

Removing the partitioning feature makes classifier lookups roughly 20%
faster when a wildcard mask is not needed, and roughly 10% faster when
a wildcard mask is needed, as tested with the test-classifier
benchmark with one lookup thread.

Found by profiling with 'perf'.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>