Fixed a bug with inproperly cleared MsgTxt in SINQAxis

Extended pmacAxis to properly deal with HRPT pmac motors which have an extra error condition

sinqEPICSApp/src/SINQAxis.cpp

@@ -12,6 +12,7 @@ SINQAxis::SINQAxis(class SINQController *pC, int axis)
   : asynMotorAxis((asynMotorController *)pC, axis),
     pC_(pC)
 {
+  updateMsgTxtFromDriver("");
 }
 
 
@@ -22,6 +23,7 @@ void SINQAxis::updateMsgTxtFromDriver(const char *value)
     setStringParam(pC_->motorMessageText_,value);
   } else {
     pC_->setIntegerParam(axisNo_,pC_->motorMessageIsFromDriver_, 0);
+    setStringParam(pC_->motorMessageText_,"");
   }  
 }