Bin two comments that say the same as the names of the functions they are for

Change-Id: I385e0ae6502eeab9e5cb536c34c64b7fa48442d0
Reviewed-on: https://gerrit.libreoffice.org/46138Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tor Lillqvist <tml@collabora.com>

include/svl/itemset.hxx

@@ -174,10 +174,8 @@ public:
         return nullptr;
     }
 
-    // Get Which-value of the item at position nPos
     sal_uInt16                  GetWhichByPos(sal_uInt16 nPos) const;
 
-    // Get item-status
     SfxItemState                GetItemState(   sal_uInt16 nWhich,
                                                 bool bSrchInParent = true,
                                                 const SfxPoolItem **ppItem = nullptr ) const;