try this
="void(window.open('http://localhost/ReportServer/Pages/ReportViewer.aspx?%2fKonsolidata_Data_Exporting_Project%2fEXPORT_REPORT_TEST&rs:Command=Render&RP_cntry="+Fields!STD_CTRY_NM.Value+"&RP_cll_typ_l1=" "+Join(Parameters!RP_cll_typ_l1.Value,"&RP_cll_typ_l1=")+"'))"