use new sdbus++ camelcase

Change I17a8d7479556596a3cf252b3f4eae9c8df547189 will change
how sdbus++ generates names which start with an acronym.
Prepare for this by keying off the SDBUSPP_NEW_CAMELCASE
define to use the new format.

Changes:
    vLAN -> vlan

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I3c5c1d0d14c7f7b0e99da57477aa117c39114021
diff --git a/network_manager.cpp b/network_manager.cpp
index 10a2573..881b767 100644
--- a/network_manager.cpp
+++ b/network_manager.cpp
@@ -180,7 +180,7 @@
         bus, objPath.string(), *this);
 }
 
-ObjectPath Manager::vLAN(IntfName interfaceName, uint32_t id)
+ObjectPath Manager::vlan(IntfName interfaceName, uint32_t id)
 {
     return interfaces[interfaceName]->createVLAN(id);
 }
diff --git a/network_manager.hpp b/network_manager.hpp
index 6815d3f..227955c 100644
--- a/network_manager.hpp
+++ b/network_manager.hpp
@@ -14,6 +14,10 @@
 #include <vector>
 #include <xyz/openbmc_project/Common/FactoryReset/server.hpp>
 
+#ifndef SDBUSPP_NEW_CAMELCASE
+#define vlan vLAN
+#endif
+
 namespace phosphor
 {
 namespace network
@@ -56,7 +60,7 @@
     Manager(sdbusplus::bus::bus& bus, const char* objPath,
             const std::string& dir);
 
-    ObjectPath vLAN(IntfName interfaceName, uint32_t id) override;
+    ObjectPath vlan(IntfName interfaceName, uint32_t id) override;
 
     /** @brief write the network conf file with the in-memory objects.
      */