OptionRomPkg: Fix GCC build failure

Remove the variable which is set but not used to pass GCC build.

Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
diff --git a/OptionRomPkg/Bus/Usb/UsbNetworking/Ax88772/Ax88772.c b/OptionRomPkg/Bus/Usb/UsbNetworking/Ax88772/Ax88772.c
index dd18a95..73d54f0 100644
--- a/OptionRomPkg/Bus/Usb/UsbNetworking/Ax88772/Ax88772.c
+++ b/OptionRomPkg/Bus/Usb/UsbNetworking/Ax88772/Ax88772.c
@@ -667,7 +667,6 @@
   UINT8* pData;

   UINT32 offset;

   RX_TX_PACKET * pRxPacket;

-  UINTN LengthInBytes;

   EFI_STATUS Status;

   

   for ( offset = 0; offset < BufLength; ){

@@ -684,7 +683,6 @@
     }

       

     pRxPacket = pNicDevice->pRxFree;

-    LengthInBytes = sizeof ( *pRxPacket ) - sizeof ( pRxPacket->pNext );

     if ( NULL == pRxPacket ) {

       Status = gBS->AllocatePool ( EfiRuntimeServicesData,

                                    sizeof( RX_TX_PACKET ),