psu-ng: Refactor VIN_UV fault detection

Split off code checking for VIN_UV fault in STATUS_WORD to its own
function.

Change-Id: Ifd07b6958885ed19c7611e10e343d1a5f10ec684
Signed-off-by: Brandon Wyman <bjwyman@gmail.com>
diff --git a/phosphor-power-supply/power_supply.hpp b/phosphor-power-supply/power_supply.hpp
index 45c4959..f36a1cc 100644
--- a/phosphor-power-supply/power_supply.hpp
+++ b/phosphor-power-supply/power_supply.hpp
@@ -568,6 +568,11 @@
     void analyzeMFRFault();
 
     /**
+     * @brief Analyzes the STATUS_WORD for a VIN_UV_FAULT indicator.
+     */
+    void analyzeVinUVFault();
+
+    /**
      * @brief D-Bus path to use for this power supply's inventory status.
      **/
     std::string inventoryPath;