Add clear method

cocotbext/eth/gmii.py

@@ -176,6 +176,11 @@ class GmiiSource(Reset):
     def idle(self):
         return self.empty() and not self.active
 
+    def clear(self):
+        self.queue.clear()
+        self.queue_occupancy_bytes = 0
+        self.queue_occupancy_frames = 0
+
     async def wait(self):
         while not self.idle():
             await RisingEdge(self.clock)
@@ -315,6 +320,11 @@ class GmiiSink(Reset):
     def idle(self):
         return not self.active
 
+    def clear(self):
+        self.queue.clear()
+        self.queue_occupancy_bytes = 0
+        self.queue_occupancy_frames = 0
+
     async def wait(self, timeout=0, timeout_unit=None):
         if not self.empty():
             return