drm/amd/display: Guard cursor idle reallow by DC debug option

[WHY]
To control whether idle optimizations reallowed after the first cursor
update.

[HOW]
Add checks to the conditions.
Reviewed-by: Duncan Ma <duncan.ma@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@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_stream.c

@@ -319,7 +319,7 @@ bool dc_stream_set_cursor_attributes(
 	program_cursor_attributes(dc, stream, attributes);
 
 	/* re-enable idle optimizations if necessary */
-	if (reset_idle_optimizations)
+	if (reset_idle_optimizations && !dc->debug.disable_dmub_reallow_idle)
 		dc_allow_idle_optimizations(dc, true);
 
 	return true;
@@ -394,7 +394,7 @@ bool dc_stream_set_cursor_position(
 
 	program_cursor_position(dc, stream, position);
 	/* re-enable idle optimizations if necessary */
-	if (reset_idle_optimizations)
+	if (reset_idle_optimizations && !dc->debug.disable_dmub_reallow_idle)
 		dc_allow_idle_optimizations(dc, true);
 
 	return true;