be2net: Allow GRE to work concurrently while a VxLAN tunnel is configured

Other tunnels like GRE break while VxLAN offloads are enabled in Skyhawk-R. To
avoid this, we should restrict offload features on a per-packet basis in such
conditions.

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>