NetworkPkg: Fix IpsecConfig GCC build failure issue

NetworkPkg: Fix IpsecConfig GCC build failure issue

This issue is caused by the string token ID for help message,
which is defined in the internal head file.
This head file is used for reference more than once. So,
multiple definition for the string token ID error will be
enrolled.

Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Zhang Lubo <lubo.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Zhang, Lubo <lubo.zhang@intel.com>