NetworkPkg: TcpDriver use EFI_D_NET for DEBUG maessage.

Tcp driver need to use EFI_D_NET to log DEBUG message,
So it becomes easy to separate/filter out debug messages
from network stack versus generic EFI_D_INFO debugs.

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

NetworkPkg/TcpDxe/TcpMisc.c

@@ -613,7 +613,7 @@ TcpSetState (
   ASSERT (State < (sizeof (mTcpStateName) / sizeof (CHAR16 *)));
 
   DEBUG (
-    (EFI_D_INFO,
+    (EFI_D_NET,
     "Tcb (%p) state %s --> %s\n",
     Tcb,
     mTcpStateName[Tcb->State],
@@ -862,7 +862,7 @@ TcpOnAppConsume (
       if (TcpOld < Tcb->RcvMss) {
 
         DEBUG (
-          (EFI_D_INFO,
+          (EFI_D_NET,
           "TcpOnAppConsume: send a window update for a window closed Tcb %p\n",
           Tcb)
           );
@@ -871,7 +871,7 @@ TcpOnAppConsume (
       } else if (Tcb->DelayedAck == 0) {
 
         DEBUG (
-          (EFI_D_INFO,
+          (EFI_D_NET,
           "TcpOnAppConsume: scheduled a delayed ACK to update window for Tcb %p\n",
           Tcb)
           );