drm/amd/display: Add a missing hook to DCN20

The struct timing_generator_funcs provides a hook for setting up the
maximum possible vertical dimension of display for OTG, as the panel
supports. DCN10 has a standard function named optc1_set_vtotal_min_max
which all ASICs can use to set the aforementioned hook. Since we did not
set it for DCN20, this commit initializes the set_vtotal_min_max with
the DCN10 function.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_optc.c

@@ -529,6 +529,7 @@ static struct timing_generator_funcs dcn20_tg_funcs = {
 		.enable_optc_clock = optc1_enable_optc_clock,
 		.set_drr = optc1_set_drr,
 		.get_last_used_drr_vtotal = optc2_get_last_used_drr_vtotal,
+		.set_vtotal_min_max = optc1_set_vtotal_min_max,
 		.set_static_screen_control = optc1_set_static_screen_control,
 		.program_stereo = optc1_program_stereo,
 		.is_stereo_left_eye = optc1_is_stereo_left_eye,