ucm: Set uc_mgr->ctl to NULL after closing it.
ucm: Set uc_mgr->ctl to NULL after closing it.

Fixes a double-free bug.

Signed-off-by: Tanu Kaskinen <87394c1d2634221151a39c7049f92721fb31e634@iki.fi>
Acked-by: Liam Girdwood <1c687ae09fa7f11acd34075a0ae6b39df2be9341@linux.intel.com>
Signed-off-by: Takashi Iwai <4596b3305151c7ee743192a95d394341e3d3b644@suse.de>

takaswie/alsa-lib,lgirdwood/alsa-lib,mengdonglin/alsa-lib,takaswie/alsa-lib,zedongchen/alsa-lib,zedongchen/alsa-lib,lgirdwood/alsa-lib,mikelima/alsa-lib,Distrotech/alsa-lib,zedongchen/alsa-lib,mengdonglin/alsa-lib,takaswie/alsa-lib,mengdonglin/alsa-lib,takaswie/alsa-lib,mikelima/alsa-lib,zedongchen/alsa-lib,Distrotech/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,mikelima/alsa-lib,tiwai/alsa-lib,Distrotech/alsa-lib,alsa-project/alsa-lib,mikelima/alsa-lib,mengdonglin/alsa-lib,tiwai/alsa-lib,mengdonglin/alsa-lib,tiwai/alsa-lib,alsa-project/alsa-lib,Distrotech/alsa-lib,tiwai/alsa-lib,mikelima/alsa-lib,Distrotech/alsa-lib,alsa-project/alsa-lib,lgirdwood/alsa-lib,zedongchen/alsa-lib,lgirdwood/alsa-lib,lgirdwood/alsa-lib