nvidia-gpu: deferred init for NvidiaGpuDevice

Adds deferred init for NvidiaGpuDevice, so that when we bind
to this, the this pointer is valid, i.e. after construction
is completed

Change-Id: I24a53d2ab9be1a2a4431368414a154b48347d2a2
Signed-off-by: Marc Olberding <molberding@nvidia.com>
diff --git a/src/nvidia-gpu/NvidiaGpuDevice.cpp b/src/nvidia-gpu/NvidiaGpuDevice.cpp
index 4bba49c..78984c5 100644
--- a/src/nvidia-gpu/NvidiaGpuDevice.cpp
+++ b/src/nvidia-gpu/NvidiaGpuDevice.cpp
@@ -46,7 +46,12 @@
     inventory = std::make_shared<Inventory>(
         conn, objectServer, name, mctpRequester,
         gpu::DeviceIdentification::DEVICE_GPU, eid, io);
+}
+
+void GpuDevice::init()
+{
     makeSensors();
+    inventory->init();
 }
 
 void GpuDevice::makeSensors()