esp32: Add explicit initialisers to silence compiler warnings.

This makes no functional change.  See similar commit
9aa58cf8Signed-off-by: Damien George <damien@micropython.org>

ports/esp32/machine_i2c.c

@@ -120,7 +120,7 @@ mp_obj_t machine_hw_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_
     // Parse args
     enum { ARG_id, ARG_scl, ARG_sda, ARG_freq, ARG_timeout };
     static const mp_arg_t allowed_args[] = {
-        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_scl, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_sda, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_freq, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 400000} },

ports/esp32/modnetwork.c

@@ -331,7 +331,7 @@ STATIC mp_obj_t esp_connect(size_t n_args, const mp_obj_t *pos_args, mp_map_t *k
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
-    wifi_config_t wifi_sta_config = {{{0}}};
+    wifi_config_t wifi_sta_config = {0};
 
     // configure any parameters that are given
     if (n_args > 1) {

ports/esp32/mphalport.c

@@ -52,7 +52,7 @@
 TaskHandle_t mp_main_task_handle;
 
 STATIC uint8_t stdin_ringbuf_array[256];
-ringbuf_t stdin_ringbuf = {stdin_ringbuf_array, sizeof(stdin_ringbuf_array)};
+ringbuf_t stdin_ringbuf = {stdin_ringbuf_array, sizeof(stdin_ringbuf_array), 0, 0};
 
 // Check the ESP-IDF error code and raise an OSError if it's not ESP_OK.
 void check_esp_err(esp_err_t code) {