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/dbus/dbuspassive.hpp b/dbus/dbuspassive.hpp
index 3813622..156be13 100644
--- a/dbus/dbuspassive.hpp
+++ b/dbus/dbuspassive.hpp
@@ -55,6 +55,7 @@
ReadReturn read(void) override;
bool getFailed(void) const override;
+ std::string getFailReason(void) const override;
void updateValue(double value, bool force);
void setValue(double value, double unscaled);