ShellPkg: Update the error prompt for ping6 command.

when we use the ping6 command without configuring the network
interface, it should give correct prompt to users.

Cc: Hegde Nagaraj P <nagaraj-p.hegde@hpe.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: Sriram Subramanian <sriram-s@hpe.com>
Reviewed-by: Hegde, Nagaraj P <nagaraj-p.hegde@hpe.com>
Reviewed-By: Wu Jiaxin <jiaxin.wu@intel.com>

ShellPkg/Library/UefiShellNetwork2CommandsLib/Ping6.c

@@ -826,7 +826,7 @@ Ping6CreateIpInstance (
   //
 
   if (HandleIndex == HandleNum) {
-    ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_PING6_SOURCE_NOT_FOUND), gShellNetwork2HiiHandle, mIp6SrcString);
+    ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_PING6_CONFIGD_NIC_NF), gShellNetwork2HiiHandle);
     Status = EFI_NOT_FOUND;
     goto ON_ERROR;
   }