doxygen: fix some function prototype description

Change-Id: I49311a643ea73143839d2f6bde976cfd76f8c67f
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6830
Tested-by: jenkins

src/jtag/drivers/jlink.c

@@ -114,8 +114,6 @@ static int jlink_flush(void);
  * @param in A pointer to store TDO data to, if NULL the data will be discarded.
  * @param in_offset A bit offset for TDO data.
  * @param length Amount of bits to transfer out and in.
- *
- * @retval This function doesn't return any value.
  */
 static void jlink_clock_data(const uint8_t *out, unsigned out_offset,
 			     const uint8_t *tms_out, unsigned tms_offset,

src/jtag/drivers/ulink.c

@@ -604,8 +604,6 @@ static int ulink_get_queue_size(struct ulink *device,
  * Clear the OpenULINK command queue.
  *
  * @param device pointer to struct ulink identifying ULINK driver instance.
- * @return on success: ERROR_OK
- * @return on failure: ERROR_FAIL
  */
 static void ulink_clear_queue(struct ulink *device)
 {