add option to specify CDPv1 or CDPv2 and separately enable or force each
Signed-off-by: Stephen Howell <howels@allthatwemight.be>
(cherry picked from commit b67182008f)
Link: https://github.com/openwrt/openwrt/pull/15299
Signed-off-by: Robert Marko <robimarko@gmail.com>