net/nfp: add infrastructure for conntrack flow merge

Add the logic to process the merge of items and actions of
pre_ct and post_ct flow. The result will be stored in a field
of merged flow.

Signed-off-by: Chaoyong He <[email protected]>

Author: hechaoyong

doc/guides/nics/features/nfp.ini

@@ -28,6 +28,7 @@ x86-64               = Y
 Usage doc            = Y
 
 [rte_flow items]
+conntrack            = Y
 eth                  = Y
 geneve               = Y
 gre                  = Y
@@ -42,6 +43,7 @@ vlan                 = Y
 vxlan                = Y
 
 [rte_flow actions]
+conntrack            = Y
 count                = Y
 drop                 = Y
 jump                 = Y