esp8266/esp_mphal: Don't swallow exceptions in dupterm's read()/write().

The idea is that if dupterm object can handle exceptions, it will handle
them itself. Otherwise, object state can be compromised and it's better
to terminate dupterm session. For example, disconnected socket will keep
throwing exceptions and dump messages about that.

esp8266/esp_mphal.c

@@ -185,12 +185,9 @@ static int call_dupterm_read(void) {
         nlr_pop();
         return *(byte*)bufinfo.buf;
     } else {
-        // Temporarily disable dupterm to avoid infinite recursion
-        mp_obj_t save_term = MP_STATE_PORT(term_obj);
         MP_STATE_PORT(term_obj) = NULL;
-        mp_printf(&mp_plat_print, "dupterm: ");
+        mp_printf(&mp_plat_print, "dupterm: Exception in read() method, deactivating: ");
         mp_obj_print_exception(&mp_plat_print, nlr.ret_val);
-        MP_STATE_PORT(term_obj) = save_term;
     }
 
     return -1;