be2net: Export tunnel offloads only when a VxLAN tunnel is created

The encapsulated offload flags shouldn't be unconditionally exported
to the stack. The stack expects offloading to work across all tunnel
types when those flags are set. This would break other tunnels (like
GRE) since be2net currently supports tunnel offload for VxLAN only.

Also, with VxLANs Skyhawk-R can offload only 1 UDP dport. If more
than 1 UDP port is added, we should disable offloads in that case too.

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