MdeModulePkg/DxeCore: Add check to ensure no possible NULL ptr deref

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

MdeModulePkg/Core/Dxe/Hand/Handle.c

@@ -1178,6 +1178,7 @@ Done:
       // EFI_ALREADY_STARTED is not an error for bus driver.
       // Return the corresponding protocol interface.
       //
+      ASSERT (Prot != NULL);
       *Interface = Prot->Interface;
     } else if (Status == EFI_UNSUPPORTED) {
       //