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>