drm/amd/display/dc/calcs/dce_calcs: Demote non-conformant kernel-doc function headers

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

 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:2753: warning: Function parameter or member 'vbios' not described in 'is_display_configuration_supported'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:2753: warning: Function parameter or member 'calcs_output' not described in 'is_display_configuration_supported'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'ctx' not described in 'bw_calcs'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'dceip' not described in 'bw_calcs'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'vbios' not described in 'bw_calcs'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'pipe' not described in 'bw_calcs'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'pipe_count' not described in 'bw_calcs'
 drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dce_calcs.c:3030: warning: Function parameter or member 'calcs_output' not described in 'bw_calcs'

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c

@@ -2725,7 +2725,7 @@ void bw_calcs_init(struct bw_calcs_dceip *bw_dceip,
 
 }
 
-/**
+/*
  * Compare calculated (required) clocks against the clocks available at
  * maximum voltage (max Performance Level).
  */
@@ -2996,13 +2996,12 @@ static bool all_displays_in_sync(const struct pipe_ctx pipe[],
 	return true;
 }
 
-/**
+/*
  * Return:
  *	true -	Display(s) configuration supported.
  *		In this case 'calcs_output' contains data for HW programming
  *	false - Display(s) configuration not supported (not enough bandwidth).
  */
-
 bool bw_calcs(struct dc_context *ctx,
 	const struct bw_calcs_dceip *dceip,
 	const struct bw_calcs_vbios *vbios,