ofp-actions: Avoid buffer overread in BUNDLE action decoding.

Reported-at: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9052
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>
decode_OFPAT_RAW_SET_DL_SRC(const struct ofp_action_dl_addr *a,
                            enum ofp_version ofp_version OVS_UNUSED,
                            struct ofpbuf *out)
{
    ofpact_put_SET_ETH_SRC(out)->mac = a->dl_addr;
    return 0;
}

decode_OFPAT_RAW_SET_DL_SRC(const struct ofp_action_dl_addr *a,
                            enum ofp_version ofp_version OVS_UNUSED,
                            struct ofpbuf *out)
{
    ofpact_put_SET_ETH_SRC(out)->mac = a->dl_addr;
    return 0;
}
