Add readability-redundant-* checks

There's a number of redundancies in our code that clang can sanitize
out.  Fix the existing problems, and enable the checks.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ie63d7b7f0777b702fbf1b23a24e1bed7b4f5183b
diff --git a/include/openbmc_dbus_rest.hpp b/include/openbmc_dbus_rest.hpp
index 8aab757..6861571 100644
--- a/include/openbmc_dbus_rest.hpp
+++ b/include/openbmc_dbus_rest.hpp
@@ -2044,7 +2044,7 @@
 
     // If accessing a single attribute, fill in and update objectPath,
     // otherwise leave destProperty blank
-    std::string destProperty = "";
+    std::string destProperty;
     const char* attrSeperator = "/attr/";
     size_t attrPosition = objectPath.find(attrSeperator);
     if (attrPosition != objectPath.npos)