net/ice/base: add reference count to tunnels

net/ice/base: add reference count to tunnels

Add a lock for protecting the tunnel table while adding, removing
and searching tunnels.

Add reference counting to tunnels so that multiple instances
of the same tunnel port can be created. Only physically
destroy the tunnel when all instances of that tunnel have been
destroyed.

Signed-off-by: Dan Nowlin <dan.nowlin@intel.com>
Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>