NetworkPkg:Fix the issue Http boot hang when network failed.

NetworkPkg:Fix the issue Http boot hang when network failed.

For both IPv4 and IPv6, when network transfer failed, such as disconnected
cable or disable http server, HTTP boot should exit back to the menu UI
rather than hang.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19335 6f19259b-4bc3-4df7-8a09-765794883524