drm/amd/display/dc/dce/dce_clock_source: Fix formatting/spelling of worthy function headers

Demote the one that provides no param descriptions.

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

 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'calc_pll_cs' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'target_pix_clk_100hz' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'ref_divider' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'post_divider' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'feedback_divider_param' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:142: warning: Function parameter or member 'fract_feedback_divider_param' not described in 'calculate_fb_and_fractional_fb_divider'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:200: warning: Function parameter or member 'calc_pll_cs' not described in 'calc_fb_divider_checking_tolerance'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:200: warning: Function parameter or member 'pll_settings' not described in 'calc_fb_divider_checking_tolerance'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:200: warning: Function parameter or member 'ref_divider' not described in 'calc_fb_divider_checking_tolerance'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:200: warning: Function parameter or member 'post_divider' not described in 'calc_fb_divider_checking_tolerance'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:200: warning: Function parameter or member 'tolerance' not described in 'calc_fb_divider_checking_tolerance'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:478: warning: Function parameter or member 'clk_src' not described in 'dce110_get_pix_clk_dividers_helper'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:478: warning: Function parameter or member 'pll_settings' not described in 'dce110_get_pix_clk_dividers_helper'
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:478: warning: Function parameter or member 'pix_clk_params' not described in 'dce110_get_pix_clk_dividers_helper'

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: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
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>