Fixes RVEL not being populated

This patch fixes the issue reported in
https://epics.anl.gov/tech-talk/2026/msg00212.php, where the RVEL field
of the motor record was not populated when writing to the motorVelocity_
paramLib entry.

motorApp/MotorSrc/asynMotorAxis.cpp

@@ -288,7 +288,12 @@ asynStatus asynMotorAxis::setDoubleParam(int function, double value)
         statusChanged_ = 1;
         status_.encoderPosition = value;
     }
-  }  
+  } else if (function == pC_->motorVelocity_) {
+    if (value != status_.velocity) {
+        statusChanged_ = 1;
+        status_.velocity = value;
+    }
+  }
   // Call the base class method
   return pC_->setDoubleParam(axisNo_, function, value);
 }