drbd: turn bitmap I/O comments into regular block comments

W=1 build warns because the bitmap I/O comments use '/**', which
marks them as kernel-doc comments even though these functions do not
document an external API.

Convert these comments to regular block comments so kernel-doc no
longer parses them.

Signed-off-by: Sukrut Heroorkar <[e-mail]>
Acked-by: Christoph Böhmwalder <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/drbd/drbd_bitmap.c

···
 	return err;
 }
 
-/**
+/*
  * drbd_bm_read() - Read the whole bitmap from its on disk location.
  * @device:	DRBD device.
  */
···
 	return bm_rw(device, BM_AIO_READ, 0);
 }
 
-/**
+/*
  * drbd_bm_write() - Write the whole bitmap to its on disk location.
  * @device:	DRBD device.
  *
···
 	return bm_rw(device, 0, 0);
 }
 
-/**
+/*
  * drbd_bm_write_all() - Write the whole bitmap to its on disk location.
  * @device:	DRBD device.
  *
···
 	return bm_rw(device, BM_AIO_COPY_PAGES, upper_idx);
 }
 
-/**
+/*
  * drbd_bm_write_copy_pages() - Write the whole bitmap to its on disk location.
  * @device:	DRBD device.
  *
···
 	return bm_rw(device, BM_AIO_COPY_PAGES, 0);
 }
 
-/**
+/*
  * drbd_bm_write_hinted() - Write bitmap pages with "hint" marks, if they have changed.
  * @device:	DRBD device.
  */