Remove unused using directive and clean up code

Author: w-ahmad

src/Columns/TableViewComboBoxColumn.cs

@@ -3,7 +3,6 @@
 using Microsoft.UI.Xaml.Controls.Primitives;
 using Microsoft.UI.Xaml.Data;
 using System;
-using WinUI.TableView.Extensions;
 
 namespace WinUI.TableView;
 
@@ -16,8 +15,7 @@ public class TableViewComboBoxColumn : TableViewBoundColumn
 {
     private Binding? _textBinding;
     private Binding? _selectedValueBinding;
-    private Func<object, object?>? _funcCompiledDisplayMemberPath;
-
+    
     /// <summary>
     /// Generates a TextBlock element for the cell.
     /// </summary>
@@ -69,8 +67,6 @@ public override FrameworkElement GenerateEditingElement(TableViewCell cell, obje
             comboBox.SetBinding(Selector.SelectedValueProperty, SelectedValueBinding);
         }
 
-        comboBox.GetBindingExpression(Selector.SelectedItemProperty)?.UpdateSource();
-
         return comboBox;
     }
 
@@ -161,4 +157,4 @@ public virtual Binding SelectedValueBinding
     /// Identifies the IsEditable dependency property.
     /// </summary>
     public static readonly DependencyProperty IsEditableProperty = DependencyProperty.Register(nameof(IsEditable), typeof(bool), typeof(TableViewComboBoxColumn), new PropertyMetadata(false));
-}
+}