iw: allow user to enable vendor synchronization when joining mesh
iw: allow user to enable vendor synchronization when joining mesh

Currently this option just disables the default neighbor offset
synchronization method. It is useful for testing.

Signed-off-by: Marco Porsch <b5e7ac3138a133832a61789f7ed20bb47e55d974@etit.tu-chemnitz.de>

Distrotech/iw,Distrotech/iw,greearb/iw-ct,chunyeow/iw,bw-oss/iw,CTU-IIG/802.11p-iw,CTU-IIG/802.11p-iw,bw-oss/iw,cozybit/iw,greearb/iw-ct,cozybit/iw,chunyeow/iw