Refine code to make it more safely.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15598 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideDxe.c

@@ -123,10 +123,11 @@ DevicePathToStr (
            TRUE
            );
   if (Text == NULL) {
-    return AllocateCopyPool (sizeof (L"?"), L"?");
-  } else {
-    return Text;
+    Text = AllocateCopyPool (sizeof (L"?"), L"?");
+    ASSERT (Text != NULL);
   }
+
+  return Text;
 }
 
 /**