psu-ng: Add accessor to get the inventory path

When creating errors, the inventory path may be needed for some of the
call outs.

Signed-off-by: Brandon Wyman <bjwyman@gmail.com>
Change-Id: I545aae603478e43909620b087c57ccd4b69d3eef
diff --git a/phosphor-power-supply/power_supply.hpp b/phosphor-power-supply/power_supply.hpp
index eb310da..ecf4d82 100644
--- a/phosphor-power-supply/power_supply.hpp
+++ b/phosphor-power-supply/power_supply.hpp
@@ -167,6 +167,11 @@
         return vinUVFault;
     }
 
+    const std::string& getInventoryPath() const
+    {
+        return inventoryPath;
+    }
+
   private:
     /** @brief systemd bus member */
     sdbusplus::bus::bus& bus;