drm/amd/display: Add DSC check to seamless boot validation

[Why & How]
We want to immediately fail seamless boot validation if DSC is active,
as VBIOS currently does not support DSC timings. Add a check for
the relevant flag in dc_validate_seamless_boot_timing.
Signed-off-by: Anthony Wang <anthony1.wang@amd.com>
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1400,6 +1400,10 @@ bool dc_validate_seamless_boot_timing(const struct dc *dc,
 	if (crtc_timing->v_sync_width != hw_crtc_timing.v_sync_width)
 		return false;
 
+	/* block DSC for now, as VBIOS does not currently support DSC timings */
+	if (crtc_timing->flags.DSC)
+		return false;
+
 	if (dc_is_dp_signal(link->connector_signal)) {
 		unsigned int pix_clk_100hz;