dpif-netdev: Increase the number of EMC entries

dpif-netdev: Increase the number of EMC entries

Prior to this commit, the number of possible entries in the Exact
Match Cache stood at 1024 per thread exacting to 0.18Mb. A typical
server system will have 2.5Mb cache per core meaning a larger EMC will
comfortably fit in. This patch increases the number of entries to 8192
per thread (1.4Mb) which in turn yields improved throughput when
processing multiple flows of traffic.

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Daniele Di Proietto <diproiettod@vmware.com>
Acked-by: Ethan Jackson <ethan@nicira.com>