-Lc++-impl: better namespace handling

Intelligent namespace handling requires much more work
so using Formatter like the rest of hidl-gen.

Test: manual with -Lc++-impl
Fixes: 37294618
Change-Id: I9593ec31b8b8dd19b09750acf10c0330f5628a58
diff --git a/Interface.cpp b/Interface.cpp
index a2fa82f..5974288 100644
--- a/Interface.cpp
+++ b/Interface.cpp
@@ -621,7 +621,7 @@
     const std::string base =
           std::string(specifyNamespaces ? "::android::" : "")
         + "sp<"
-        + (specifyNamespaces ? fullName() : partialCppName())
+        + fullName()
         + ">";
 
     switch (mode) {