[control] minor logic optimization

Author: stnolting

rtl/core/neorv32_cpu_control.vhd

@@ -816,9 +816,7 @@ begin
            (trap_ctrl.exc_buf(exc_saccess_c) = '1') or (trap_ctrl.exc_buf(exc_laccess_c) = '1') or -- access exception
            (trap_ctrl.exc_buf(exc_salign_c)  = '1') or (trap_ctrl.exc_buf(exc_lalign_c)  = '1') or -- alignment exception
            (trap_ctrl.exc_buf(exc_illegal_c) = '1') then -- illegal instruction exception
-          if (RISCV_ISA_Zaamo and (opcode(2) = opcode_amo_c(2))) or (opcode(5) = '0') then -- atomic operation / normal load
-            ctrl_nxt.rf_wb_en <= '1'; -- allow write-back to register file (won't happen in case of exception)
-          end if;
+          ctrl_nxt.rf_wb_en    <= not ctrl.lsu_rw; -- write-back to register file if read operation (won't happen in case of exception)
           exe_engine_nxt.state <= EX_DISPATCH;
         end if;