Fixed syntax error

common/firmware/hdl/TrackFinder.vhd

@@ -72,7 +72,7 @@ begin
                     end if;
                 end loop;
             end if;
-            valid_event <= and_reduce(valid_event_array) and headder_start;
+            valid_event <= and_reduce(valid_event_array) and header_start;
 
             if valid_event then
                 histogram_input.valid <= '1';