[Edgecore][AS9726-32D] Read the data when the PSU is in the power-goo…

…d state.

device/accton/x86_64-accton_as9726_32d-r0/sonic_platform/psu.py

@@ -72,6 +72,9 @@ def get_voltage(self):
             A float number, the output voltage in volts,
             e.g. 12.1
         """
+        if self.get_status() is not True:
+            return 0
+
         vout_path = "{}{}".format(self.hwmon_path, 'psu_v_out')        
         vout_val=self._api_helper.read_txt_file(vout_path)
         if vout_val is not None:
@@ -85,6 +88,9 @@ def get_current(self):
         Returns:
             A float number, the electric current in amperes, e.g 15.4
         """
+        if self.get_status() is not True:
+            return 0
+
         iout_path = "{}{}".format(self.hwmon_path, 'psu_i_out')        
         val=self._api_helper.read_txt_file(iout_path)
         if val is not None:
@@ -98,6 +104,9 @@ def get_power(self):
         Returns:
             A float number, the power in watts, e.g. 302.6
         """
+        if self.get_status() is not True:
+            return 0
+
         pout_path = "{}{}".format(self.hwmon_path, 'psu_p_out')        
         val=self._api_helper.read_txt_file(pout_path)
         if val is not None: