ShellPkg: Fix issue about Ifconfig6 -r command.

ShellPkg: Fix issue about Ifconfig6 -r command.

Follow the Shell Spec, when the interface name is Specified,
we need to refresh the Ipv6 configuration.

Cc: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Wu Jiaxin <jiaxin.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
Reviewed-by: Hegde Nagaraj P <nagaraj-p.hegde@hpe.com>
Reviewed-by: Sriram Subramanian <sriram-s@hpe.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-By: Wu Jiaxin <jiaxin.wu@intel.com>