refactor(rng): move rng read data function to rng_ll.h and update docs of RNG source

components/hal/esp32c5/include/hal/rng_ll.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2025-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -8,6 +8,8 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include "soc/soc.h"
+#include "soc/lpperi_reg.h"
 #include "soc/lpperi_struct.h"
 #include "hal/lp_clkrst_ll.h"
 
@@ -17,6 +19,16 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Read random data from RNG
+ *
+ * @return 32-bit random data
+ */
+static inline uint32_t rng_ll_read_data(void)
+{
+    return REG_READ(LPPERI_RNG_DATA_SYNC_REG);
+}
+
 /**
  * @brief Enable or disable RNG sampling.
  *