psu-ng: Retrieve PSU VPD keyword from D-Bus.

Extract PSU VPD keyword from D-Bus and assign associated string value to
VPD string.

Change-Id: Iaf8112df7e388e6fd4363798c92d76f0a67e3b69
Signed-off-by: Faisal Awada <faisal@us.ibm.com>
diff --git a/phosphor-power-supply/power_supply.hpp b/phosphor-power-supply/power_supply.hpp
index 097cac6..304185e 100644
--- a/phosphor-power-supply/power_supply.hpp
+++ b/phosphor-power-supply/power_supply.hpp
@@ -1045,6 +1045,16 @@
      * @brief The device driver name
      */
     std::string driverName;
+
+    /**
+     * @brief Retrieve PSU VPD keyword from D-Bus
+     *
+     * It retrieves PSU VPD keyword from D-Bus and assign the associated
+     * string to vpdStr.
+     * @param[in] keyword - The VPD search keyword
+     * @param[out] vpdStr - The VPD string associated with the keyword.
+     */
+    void getPsuVpdFromDbus(const std::string& keyword, std::string& vpdStr);
 };
 
 } // namespace phosphor::power::psu