drm/amd/display/dc/core/dc_stat: Convert a couple of doc headers to kerneldoc format

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stat.c:38: warning: Cannot understand  *****************************************************************************
 drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stat.c:76: warning: Cannot understand  *****************************************************************************

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Mustapha Ghaddar <mghaddar@amd.com>
Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Cc: Jasdeep Dhillon <jdhillon@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_stat.c

@@ -35,19 +35,15 @@
  */
 
 /**
- *****************************************************************************
- *  Function: dc_stat_get_dmub_notification
+ *  dc_stat_get_dmub_notification
  *
- *  @brief
  * Calls dmub layer to retrieve dmub notification
  *
- *  @param
- *		[in] dc: dc structure
- *		[in] notify: dmub notification structure
+ * @dc: dc structure
+ * @notify: dmub notification structure
  *
- *  @return
+ * Returns
  *     None
- *****************************************************************************
  */
 void dc_stat_get_dmub_notification(const struct dc *dc, struct dmub_notification *notify)
 {
@@ -73,19 +69,15 @@ void dc_stat_get_dmub_notification(const struct dc *dc, struct dmub_notification
 }
 
 /**
- *****************************************************************************
- *  Function: dc_stat_get_dmub_dataout
+ * dc_stat_get_dmub_dataout
  *
- *  @brief
  * Calls dmub layer to retrieve dmub gpint dataout
  *
- *  @param
- *		[in] dc: dc structure
- *		[in] dataout: dmub gpint dataout
+ * @dc: dc structure
+ * @dataout: dmub gpint dataout
  *
- *  @return
+ * Returns
  *     None
- *****************************************************************************
  */
 void dc_stat_get_dmub_dataout(const struct dc *dc, uint32_t *dataout)
 {