Reg move support for nicira experimenter fields

Reg move support for nicira experimenter fields

Reg move action, with the introduction of experimenter oxm fields, was
redefined to be able to include 8 oxm byte headers vs the standard 4
byte headers. This patch changes the openflowplugin encoding of this
action to align it with the spec.

From [1], the structre of reg move action is

struct nx_action_reg_move {
    ovs_be16 type;              // OFPAT_EXPERIMENTER = 0xFFFF
    ovs_be16 len;
    ovs_be32 vendor;            // NX_VENDOR_ID = 0x00002320
    ovs_be16 subtype;           // NXAST_REG_MOVE = 6
    ovs_be16 n_bits;            // Number of bits.
    ovs_be16 src_ofs;           // Starting bit offset in source.
    ovs_be16 dst_ofs;           // Starting bit offset in destination.
    /* Followed by:
     * - OXM/NXM header for source field (4 or 8 bytes).
     * - OXM/NXM header for destination field (4 or 8 bytes).
     * - Padding with 0-bytes to a multiple of 8 bytes, if necessary. */
};

[1] https://github.com/openvswitch/ovs/blob/master/lib/ofp-actions.c

Change-Id: I80ff8de77ef960a17c72f3aecc2bc62ba39f32cb
JIRA: OPNFLWPLUG-1017
Signed-off-by: Jaime Caamaño Ruiz <jcaamano@suse.com>