[DPDK] Add ability to set pmd_rxq_affinity for dpdk interfaces

This enables a more fine tuned dpdk for better performance.
More details on pmd-rxq-affinity config:
http://docs.openvswitch.org/en/latest/howto/dpdk/

Change-Id: I630c6af94ff733619fb175f522fc515984862ff6
diff --git a/README.rst b/README.rst
index e6d251b..0a505f1 100644
--- a/README.rst
+++ b/README.rst
@@ -1040,6 +1040,7 @@
             enabled: true
             type: dpdk_ovs_port
             n_rxq: 2
+            pmd_rxq_affinity: "0:1,1:2"
             bridge: br-prv
             mtu: 9000
           br-prv:
@@ -1070,6 +1071,7 @@
             enabled: true
             type: dpdk_ovs_port
             n_rxq: 2
+            pmd_rxq_affinity: "0:1,1:2"
             mtu: 9000
           dpdk_first_nic:
             name: ${_param:primary_first_nic}
@@ -1079,6 +1081,7 @@
             enabled: true
             type: dpdk_ovs_port
             n_rxq: 2
+            pmd_rxq_affinity: "0:1,1:2"
             mtu: 9000
           dpdkbond0:
             enabled: true