pcbnew GAL: Fix bouncing zoom on mouse wheel scroll in Windows

Handling wxEVT_SCROLLWIN_LINE{UP,DOWN} executes the scroll event handler
too many times causing zoom bounces.

Fixes: lp:1562173
* https://bugs.launchpad.net/kicad/+bug/1562173

common/view/wx_view_controls.cpp

@@ -71,10 +71,6 @@ WX_VIEW_CONTROLS::WX_VIEW_CONTROLS( VIEW* aView, wxScrolledCanvas* aParentPanel
                             wxScrollWinEventHandler( WX_VIEW_CONTROLS::onScroll ), NULL, this );
     m_parentPanel->Connect( wxEVT_SCROLLWIN_PAGEDOWN,
                             wxScrollWinEventHandler( WX_VIEW_CONTROLS::onScroll ), NULL, this );
-    m_parentPanel->Connect( wxEVT_SCROLLWIN_LINEUP,
-                            wxScrollWinEventHandler( WX_VIEW_CONTROLS::onScroll ), NULL, this );
-    m_parentPanel->Connect( wxEVT_SCROLLWIN_LINEDOWN,
-                            wxScrollWinEventHandler( WX_VIEW_CONTROLS::onScroll ), NULL, this );
 
     m_panTimer.SetOwner( this );
     this->Connect( wxEVT_TIMER,