drm/amd/display: Validate hw_points_num before using it

[WHAT]
hw_points_num is 0 before ogam LUT is programmed; however, function
"dwb3_program_ogam_pwl" assumes hw_points_num is always greater than 0,
i.e. substracting it by 1 as an array index.

[HOW]
Check hw_points_num is not equal to 0 before using it.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_dwb_cm.c

@@ -243,6 +243,9 @@ static bool dwb3_program_ogam_lut(
 		return false;
 	}
 
+	if (params->hw_points_num == 0)
+		return false;
+
 	REG_SET(DWB_OGAM_CONTROL, 0, DWB_OGAM_MODE, 2);
 
 	current_mode = dwb3_get_ogam_current(dwbc30);