drm/amd/display: Minor code cleanup

[WHY]
There is an extra null check for fs_params in the
build_freesync_hdr function detected by Smatch.

[HOW]
1) Remove the extra null check since it is checked in the
caller.
Signed-off-by: NSivapiriyanKumarasamy <sivapiriyan.kumarasamy@amd.com>
Reviewed-by: NAric Cyr <Aric.Cyr@amd.com>
Acked-by: NLeo Li <sunpeng.li@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/modules/color/color_gamma.c

@@ -823,7 +823,7 @@ static bool build_freesync_hdr(struct pwl_float_data_ex *rgb_regamma,
 	bool is_clipped = false;
 	struct fixed31_32 sdr_white_level;
 
-	if (fs_params == NULL || fs_params->max_content == 0 ||
+	if (fs_params->max_content == 0 ||
 			fs_params->max_display == 0)
 		return false;