Use interfaceDescriptor instead of interfaceChain

wherever suits. Sementically, interfaceDescriptor
returns the first element of interfaceChain; use
interfaceDescriptor when the rest of the elements
aren't used.

Bug: 34136228

Test: hidl_test
Change-Id: Id7650788a00a37a6d0fcb574547371965ddf4a04
diff --git a/transport/HidlPassthroughSupport.cpp b/transport/HidlPassthroughSupport.cpp
index 2e1671d..43724f9 100644
--- a/transport/HidlPassthroughSupport.cpp
+++ b/transport/HidlPassthroughSupport.cpp
@@ -28,9 +28,9 @@
         // doesn't know how to handle it.
         return iface;
     }
-    std::string myDescriptor = getDescriptor(iface.get());
+    std::string myDescriptor = details::getDescriptor(iface.get());
     if (myDescriptor.empty()) {
-        // interfaceChain fails
+        // interfaceDescriptor fails
         return nullptr;
     }
     auto func = gBsConstructorMap.get(myDescriptor, nullptr);