drm/amd/display: Enable use of dmub iff dmcu is disabled

[Why & How]
DMUB command table should be allowed to be used
only if dmcu is explicitly disabled.

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -1906,6 +1906,8 @@ static bool dcn21_resource_construct(
 			BREAK_TO_DEBUGGER();
 			goto create_fail;
 		}
+
+		dc->debug.dmub_command_table = false;
 	}
 
 	if (dc->config.disable_dmcu) {