8273186: Remove leftover comment about sparse remembered set in G1 He…

…apRegionRemSet

Reviewed-by: ayang

src/hotspot/share/gc/g1/heapRegionRemSet.hpp

@@ -56,7 +56,6 @@ class HeapRegionRemSet : public CHeapObj<mtGC> {
 public:
   HeapRegionRemSet(HeapRegion* hr, G1CardSetConfiguration* config);
 
-  // Setup sparse and fine-grain tables sizes.
   bool cardset_is_empty() const {
     return _card_set.is_empty();
   }