refactor(ledc): move sleep retention config into driver layer

Move per-target LEDC regdma retention descriptors out of esp_hal_ledc
and into
esp_driver_ledc so the driver owns its backup scope and restore flow.

components/esp_driver_ledc/include/esp_private/ledc_priv.h

@@ -0,0 +1,51 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "soc/soc_caps.h"
+#include "hal/ledc_ll.h"
+#include "hal/ledc_types.h"
+
+#if SOC_PAU_SUPPORTED
+#include "soc/regdma.h"
+#include "soc/retention_periph_defs.h"
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if SOC_PAU_SUPPORTED
+
+#if SOC_LIGHT_SLEEP_SUPPORTED
+#if SOC_PM_SUPPORT_PMU_MODEM_STATE
+#define LEDC_RETENTION_ENTRY        (ENTRY(0) | ENTRY(2))
+#else
+#define LEDC_RETENTION_ENTRY        (ENTRY(0))
+#endif
+#else
+#define LEDC_RETENTION_ENTRY        REGDMA_SW_TRIGGER_ENTRY
+#endif
+
+typedef struct {
+    const regdma_entries_config_t *regdma_entry_array;
+    uint32_t array_size;
+} ledc_sub_reg_retention_info_t;
+
+typedef struct {
+    ledc_sub_reg_retention_info_t common;
+    ledc_sub_reg_retention_info_t timer[SOC_LEDC_TIMER_NUM];
+    ledc_sub_reg_retention_info_t channel[SOC_LEDC_CHANNEL_NUM];
+    const periph_retention_module_t module_id;
+} ledc_reg_retention_info_t;
+
+extern const ledc_reg_retention_info_t ledc_reg_retention_info[LEDC_LL_GET(GROUP_NUM)];
+#endif
+
+#ifdef __cplusplus
+}
+#endif