ShellPkg: Remove the unused local variable.

Remove the unused local variable to refine the code.

Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc:Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

ShellPkg/Application/Shell/ShellProtocol.c

@@ -1738,10 +1738,7 @@ EfiShellExecute(
   CHAR16                    *Temp;
   EFI_DEVICE_PATH_PROTOCOL  *DevPath;
   UINTN                     Size;
-  EFI_STATUS                CalleeStatusCode;
 
-  CalleeStatusCode = EFI_SUCCESS;
-  
   if ((PcdGet8(PcdShellSupportLevel) < 1)) {
     return (EFI_UNSUPPORTED);
   }