drm/i915/gvt: Update force-to-nonpriv register whitelist

Host print below warning message when creating guest:
    "gvt: vgpu(1) Invalid FORCE_NONPRIV write 10002349".

Add register 0x2348 in force-to-nonpriv whitelist as required
by guest.

Signed-off-by: Gao, Fred <fred.gao@intel.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>