Vlv2TbltDevicePkg: Use PI Spec SMBUS2 PPI

* Switch from Intel Framework SMBUS PPI to the PI Spec
  SMBUS2 PPI.
* Remove unused SmbusLib.  Use SmbusLibNull instead.

Cc: Zailiang Sun <zailiang.sun@intel.com>
Cc: Yi Qian <yi.qian@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-By: Zailiang Sun <zailiang.sun@intel.com>