drm/gma500/mdfld_dsi_output: Demote a couple of kernel-doc formatting abuses

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

 drivers/gpu/drm/gma500/mdfld_dsi_output.c:71: warning: Function parameter or member 'dev' not described in 'mdfld_dsi_gen_fifo_ready'
 drivers/gpu/drm/gma500/mdfld_dsi_output.c:71: warning: Function parameter or member 'gen_fifo_stat_reg' not described in 'mdfld_dsi_gen_fifo_ready'
 drivers/gpu/drm/gma500/mdfld_dsi_output.c:71: warning: Function parameter or member 'fifo_stat' not described in 'mdfld_dsi_gen_fifo_ready'
 drivers/gpu/drm/gma500/mdfld_dsi_output.c:95: warning: Function parameter or member 'dsi_config' not described in 'mdfld_dsi_brightness_init'
 drivers/gpu/drm/gma500/mdfld_dsi_output.c:95: warning: Function parameter or member 'pipe' not described in 'mdfld_dsi_brightness_init'

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: jim liu <jim.liu@intel.com>
Cc: Jackie Li <yaodong.li@intel.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115181601.3432599-22-lee.jones@linaro.org

drivers/gpu/drm/gma500/mdfld_dsi_output.c

@@ -63,7 +63,7 @@ static int __init parse_LABC_control(char *arg)
 early_param("LABC", parse_LABC_control);
 #endif
 
-/**
+/*
  * Check and see if the generic control or data buffer is empty and ready.
  */
 void mdfld_dsi_gen_fifo_ready(struct drm_device *dev, u32 gen_fifo_stat_reg,
@@ -85,7 +85,7 @@ void mdfld_dsi_gen_fifo_ready(struct drm_device *dev, u32 gen_fifo_stat_reg,
 					gen_fifo_stat_reg);
 }
 
-/**
+/*
  * Manage the DSI MIPI keyboard and display brightness.
  * FIXME: this is exported to OSPM code. should work out an specific
  * display interface to OSPM.