[PATCH] MdeModulePkg/EhciDxe: call EhcFreeUrb when int-transfer completes

[Ruiyu Ni <ruiyu.ni@intel.com>]

It didn't cause big issues when VT-d was disabled.
But in VT-d enabled platform, lack of EhcFreeUrb call caused
the DMA data was not moved back to user's buffer.
It caused the correct data cannot be got through sync interrupt
transfer.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
---
 MdeModulePkg/Bus/Pci/EhciDxe/Ehci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Bus/Pci/EhciDxe/Ehci.c b/MdeModulePkg/Bus/Pci/EhciDxe/Ehci.c
index 5173a9d599..f18ee82261 100644
--- a/MdeModulePkg/Bus/Pci/EhciDxe/Ehci.c
+++ b/MdeModulePkg/Bus/Pci/EhciDxe/Ehci.c
@@ -11,7 +11,7 @@
   and companion host controller when UHCI or OHCI gets attached earlier than EHCI and a 
   USB 2.0 device inserts.
 
-Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
@@ -1220,6 +1220,7 @@ EhcSyncInterruptTransfer (
     Status = EFI_SUCCESS;
   }
 
+  EhcFreeUrb (Ehc, Urb);
 ON_EXIT:
   Ehc->PciIo->Flush (Ehc->PciIo);
   gBS->RestoreTPL (OldTpl);
-- 
2.15.1.windows.2