staging: iio: ad9832: kernel-doc fixes

Fixes a W=1 warning.
-Added ``:`` to lock parameter in 'ad9832_state' description.
-It's a reference comment so removed /**

Signed-off-by: Mugilraj Dhavachelvan <dmugil2000@gmail.com>
Link: https://lore.kernel.org/r/20210315133711.26860-1-dmugil2000@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/frequency/ad9832.c

@@ -86,7 +86,7 @@
  * @freq_msg:		tuning word spi message
  * @phase_xfer:		tuning word spi transfer
  * @phase_msg:		tuning word spi message
- * @lock		protect sensor state
+ * @lock:		protect sensor state
  * @data:		spi transmit buffer
  * @phase_data:		tuning word spi transmit buffer
  * @freq_data:		tuning word spi transmit buffer
@@ -248,7 +248,7 @@ error_ret:
 	return ret ? ret : len;
 }
 
-/**
+/*
  * see dds.h for further information
  */