Check that HarnessClockInstantiator doesn't receive requests for similarly-named-clocks with different frequencies (#1460)

generators/chipyard/src/main/scala/HarnessClocks.scala

@@ -21,9 +21,15 @@ trait HarnessClockInstantiator {
 
   // request a clock bundle at a particular frequency
   def requestClockBundle(name: String, freqRequested: Double): ClockBundle = {
-    val clockBundle = Wire(new ClockBundle(ClockBundleParameters()))
-    _clockMap(name) = (freqRequested, clockBundle)
-    clockBundle
+    if (_clockMap.contains(name)) {
+      require(freqRequested == _clockMap(name)._1,
+        s"Request clock freq = $freqRequested != previously requested ${_clockMap(name)._2} for requested clock $name")
+      _clockMap(name)._2
+    } else {
+      val clockBundle = Wire(new ClockBundle(ClockBundleParameters()))
+      _clockMap(name) = (freqRequested, clockBundle)
+      clockBundle
+    }
   }
 
   // refClock is the clock generated by TestDriver that is