fix typo between dest/src and send/recv

ntttcp/ntttcp.TESTGEN.ps1

@@ -8,8 +8,8 @@ Param(
     [parameter(Mandatory=$true)]  [string] $DestIp,
     [parameter(Mandatory=$true)]  [string] $SrcIp,
     [parameter(Mandatory=$true)]  [ValidateScript({Test-Path $_ -PathType Container})] [String] $OutDir = "",
-    [parameter(Mandatory=$true)]  [string] $SendDir,
-    [parameter(Mandatory=$true)]  [string] $RecvDir
+    [parameter(Mandatory=$true)]  [string] $DestDir,
+    [parameter(Mandatory=$true)]  [string] $SrcDir
 )
 $scriptName = $MyInvocation.MyCommand.Name