NetworkPkg: Replace the internal function with exposed one

NetworkPkg: Replace the internal function with exposed one

This patch is used to replace the internal function with
the exposed one defined in NetLib.h.

Cc: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Cc: El-Haj-Mahmoud Samer <samer.el-haj-mahmoud@hpe.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>