Fix print of "soft reboot" when the user presses ^D

The logic of the main loop was changed between version 7 and 8.
[Commit](9307b62)
Something is wrong with the existing version 8 logic so the serial
write of "soft reboot" is never executed when the user does a
soft reboot.
A consequence of this is that tools like `tools/pyboard.py`, `ampy`
and `mpremote` are not able to activate the raw REPL since they
execute a soft reboot and wait for this to be printed to the console.

Author: xorbit

main.c

@@ -1078,15 +1078,17 @@ int __attribute__((used)) main(void) {
     int exit_code = PYEXEC_FORCED_EXIT;
     bool skip_repl = true;
     bool simulate_reset = true;
+    bool first_run = true;
     for (;;) {
         if (!skip_repl) {
             exit_code = run_repl(get_safe_mode());
             supervisor_set_run_reason(RUN_REASON_REPL_RELOAD);
         }
         if (exit_code == PYEXEC_FORCED_EXIT) {
-            if (!simulate_reset) {
+            if (!first_run) {
                 serial_write_compressed(translate("soft reboot\n"));
             }
+            first_run = false;
             if (pyexec_mode_kind == PYEXEC_MODE_FRIENDLY_REPL) {
                 // If code.py did a fake deep sleep, pretend that we
                 // are running code.py for the first time after a hard