treewide: Clean up string parameters

Change-Id: I0d3ea6a83465181d3edec1587ff824103489072e
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/vlan_interface.cpp b/src/vlan_interface.cpp
index 67074f0..efd1341 100644
--- a/src/vlan_interface.cpp
+++ b/src/vlan_interface.cpp
@@ -17,7 +17,8 @@
 using namespace phosphor::logging;
 using namespace sdbusplus::xyz::openbmc_project::Common::Error;
 
-VlanInterface::VlanInterface(sdbusplus::bus_t& bus, const std::string& objPath,
+VlanInterface::VlanInterface(sdbusplus::bus_t& bus,
+                             stdplus::const_zstring objPath,
                              const config::Parser& config, bool nicEnabled,
                              uint32_t vlanID, EthernetInterface& intf,
                              Manager& parent) :