print zone failsafe reason when enter failsafe mode

Tested:
```
Jun 24 01:52:45 bmc sel-logger[640]: cpu0_nbm critical high threshold assert. Reading=49.000000 Threshold=45.000000.
Jun 24 01:52:46 bmc swampd[2944]: Zone 2 fans, entering failsafe mode, output pwm: 100
Jun 24 01:52:46 bmc swampd[2944]: Fail sensor: cpu0_nbm, reason: Sensor threshold asserted
Jun 24 01:52:46 bmc swampd[2944]: Zone 0 fans, entering failsafe mode, output pwm: 100
Jun 24 01:52:46 bmc swampd[2944]: Fail sensor: cpu0_nbm, reason: Sensor threshold asserted
```

Signed-off-by: Harvey Wu <Harvey.Wu@quantatw.com>
Change-Id: I607d01b6bed11b00a40153db6521a9c9d23da519
diff --git a/test/zone_mock.hpp b/test/zone_mock.hpp
index 885a2c4..7d08f63 100644
--- a/test/zone_mock.hpp
+++ b/test/zone_mock.hpp
@@ -43,6 +43,9 @@
     MOCK_CONST_METHOD0(getManualMode, bool());
     MOCK_CONST_METHOD0(getFailSafeMode, bool());
     MOCK_METHOD0(getFailSafePercent, double());
+    MOCK_CONST_METHOD0(
+        getFailSafeSensors,
+        std::map<std::string, std::pair<std::string, double>>(void));
     MOCK_CONST_METHOD0(getZoneID, int64_t());
 
     MOCK_CONST_METHOD0(getCycleIntervalTime, uint64_t());