table: Fix disabled sort field change to default (#451)

Co-authored-by: linxin <xin.lin@longbridge-inc.com>

crates/ui/src/table.rs

@@ -535,9 +535,11 @@ where
             if ix == col_ix {
                 col_group.sort = Some(sort);
             } else {
+                if col_group.sort.is_some() {
                     col_group.sort = Some(ColSort::Default);
                 }
             }
+        }
 
         self.delegate_mut().perform_sort(col_ix, sort, cx);