selftests: openvswitch: parse trunc action

The trunc action was supported decode-able but not parse-able. Add
support for parsing the action string.
Reviewed-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Link: https://patch.msgid.link/20240704085710.353845-10-amorenoz@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/openvswitch/ovs-dpctl.py

@@ -863,6 +863,19 @@ class ovsactions(nla):
                 self["attrs"].append(["OVS_ACTION_ATTR_USERSPACE", uact])
                 parsed = True
 
+            elif parse_starts_block(actstr, "trunc(", False):
+                parencount += 1
+                actstr, val = parse_extract_field(
+                    actstr,
+                    "trunc(",
+                    r"([0-9]+)",
+                    int,
+                    False,
+                    None,
+                )
+                self["attrs"].append(["OVS_ACTION_ATTR_TRUNC", val])
+                parsed = True
+
             actstr = actstr[strspn(actstr, ", ") :]
             while parencount > 0:
                 parencount -= 1