[sycl-post-link][NFC] Return accidentally reverted change (#4726)

Returned back small piece of code which was accidentally reverted
in #4693

Author: AlexeySachkov

llvm/tools/sycl-post-link/sycl-post-link.cpp

@@ -319,7 +319,7 @@ static void collectKernelModuleMap(
     }
     case Scope_Global:
       // the map key is not significant here
-      ResKernelModuleMap["<GLOBAL>"].push_back(&F);
+      ResKernelModuleMap[GLOBAL_SCOPE_NAME].push_back(&F);
       break;
     }
   }