drm/amd/display: don't use /** for non-kernel-doc comments

Change a static function's comment from "/**" (indicating kernel-doc
notation) to "/*" (indicating a regular C language comment).
This prevents multiple kernel-doc warnings:

  drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:4343: warning: Function parameter or member 'max_supported_frl_bw_in_kbps' not described in 'intersect_frl_link_bw_support'
  drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:4343: warning: Function parameter or member 'hdmi_encoded_link_bw' not described in 'intersect_frl_link_bw_support'
  drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link_dp.c:4343: warning: expecting prototype for Return PCON's post FRL link training supported BW if its non(). Prototype was for intersect_frl_link_bw_support() instead

Fixes: c022375a ("drm/amd/display: Add DP-HDMI FRL PCON Support in DC")
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Fangzhi Zuo <Jerry.Zuo@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4698,7 +4698,7 @@ uint32_t dc_link_bw_kbps_from_raw_frl_link_rate_data(uint8_t bw)
 	return 0;
 }
 
-/**
+/*
  * Return PCON's post FRL link training supported BW if its non-zero, otherwise return max_supported_frl_bw.
  */
 static uint32_t intersect_frl_link_bw_support(