drm/amd/display: reset dcn31 SMU mailbox on failures

commit 83293f7 upstream.

Otherwise future commands may fail as well leading to downstream
problems that look like they stemmed from a timeout the first time
but really didn't.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn31/dcn31_smu.c

@@ -119,6 +119,12 @@ int dcn31_smu_send_msg_with_param(
 
 	result = dcn31_smu_wait_for_response(clk_mgr, 10, 200000);
 
+	if (result == VBIOSSMC_Result_Failed) {
+		ASSERT(0);
+		REG_WRITE(MP1_SMN_C2PMSG_91, VBIOSSMC_Result_OK);
+		return -1;
+	}
+
 	if (IS_SMU_TIMEOUT(result)) {
 		ASSERT(0);
 		dm_helpers_smu_timeout(CTX, msg_id, param, 10 * 200000);