global: fix some potential out-of-bounds issue

...that found by Coverity Scan

components/driver/rmt.c

@@ -713,8 +713,9 @@ esp_err_t rmt_config(const rmt_config_t *rmt_param)
 static void IRAM_ATTR rmt_fill_memory(rmt_channel_t channel, const rmt_item32_t *item,
                                       uint16_t item_num, uint16_t mem_offset)
 {
-    volatile uint32_t *to = (volatile uint32_t *)&RMTMEM.chan[channel].data32[mem_offset].val;
     uint32_t *from = (uint32_t *)item;
+    volatile uint32_t *to = (volatile uint32_t *)&RMTMEM.chan[channel].data32[0].val;
+    to += mem_offset;
     while (item_num--) {
         *to++ = *from++;
     }

components/esp_system/esp_ipc.c

@@ -107,7 +107,7 @@ static void esp_ipc_init(void) __attribute__((constructor));
 
 static void esp_ipc_init(void)
 {
-    char task_name[15];
+    char task_name[configMAX_TASK_NAME_LEN];
 
     for (int i = 0; i < portNUM_PROCESSORS; ++i) {
         snprintf(task_name, sizeof(task_name), "ipc%d", i);

components/vfs/vfs.c

@@ -167,7 +167,7 @@ esp_err_t esp_vfs_register_with_id(const esp_vfs_t *vfs, void *ctx, esp_vfs_id_t
 
 esp_err_t esp_vfs_unregister_with_id(esp_vfs_id_t vfs_id)
 {
-    if (vfs_id < 0 || vfs_id >= MAX_FDS || s_vfs[vfs_id] == NULL) {
+    if (vfs_id < 0 || vfs_id >= VFS_MAX_COUNT || s_vfs[vfs_id] == NULL) {
         return ESP_ERR_INVALID_ARG;
     }
     vfs_entry_t* vfs = s_vfs[vfs_id];