drm/amd/display: initialize backlight_ramping_override to false

[Why]
Stack variable params.backlight_ramping_override is uninitialized, so it
contains junk data

[How]
Initialize the variable to false
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Josip Pavic <Josip.Pavic@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1961,6 +1961,7 @@ static int dm_late_init(void *handle)
 		linear_lut[i] = 0xFFFF * i / 15;
 
 	params.set = 0;
+	params.backlight_ramping_override = false;
 	params.backlight_ramping_start = 0xCCCC;
 	params.backlight_ramping_reduction = 0xCCCCCCCC;
 	params.backlight_lut_array_size = 16;