drm/amd/display: Disable IPS when it is not allowed.

[Why&How]
Add flag to disable IPS when it is not allowed.
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: JinZe.Xu <jinze.xu@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/dc.h

@@ -924,6 +924,7 @@ struct dc_debug_options {
 	bool disable_z9_mpc;
 	unsigned int force_fclk_khz;
 	bool enable_tri_buf;
+	bool ips_disallow_entry;
 	bool dmub_offload_enabled;
 	bool dmcub_emulation;
 	bool disable_idle_power_optimizations;

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

@@ -1506,6 +1506,8 @@ void dc_dmub_srv_apply_idle_power_optimizations(const struct dc *dc, bool allow_
 	if (!dc_dmub_srv || !dc_dmub_srv->dmub)
 		return;
 
+	allow_idle &= (!dc->debug.ips_disallow_entry);
+
 	if (dc_dmub_srv->idle_allowed == allow_idle)
 		return;