drm/amd/powerplay:clean up the residual mutex for smu_hw_init

The mutex for procting SMU during hw_init was removed as system
will be deadlock when smu_populate_umd_state_clk try get SMU mutex.
Therefore need remove the residual mutex from failed path.
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/amdgpu_smu.c

@@ -1044,7 +1044,6 @@ static int smu_hw_init(void *handle)
 	return 0;
 
 failed:
-	mutex_unlock(&smu->mutex);
 	return ret;
 }