iio: frequency: ad9523: correct kernel-doc bad line warning

Insert a "*" in the kernel-doc line to resolve a warning:

Warning: include/linux/iio/frequency/ad9523.h:47 bad line:
 LSB = 1/2 of a period of the divider input clock.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: rddunlap

include/linux/iio/frequency/ad9523.h

@@ -45,7 +45,7 @@ enum ref_sel_mode {
  * @output_dis: Disables, powers down the entire channel.
  * @driver_mode: Output driver mode (logic level family).
  * @divider_phase: Divider initial phase after a SYNC. Range 0..63
-		   LSB = 1/2 of a period of the divider input clock.
+ *		   LSB = 1/2 of a period of the divider input clock.
  * @channel_divider: 10-bit channel divider.
  * @extended_name: Optional descriptive channel name.
  */