isdn/capi: unregister capictr notifier after init failure

capidrv_init() could leave capictr notifier dangling after init
failure.  Fix it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NJan Kiszka <jan.kiszka@web.de>

drivers/isdn/capi/capidrv.c

@@ -2297,6 +2297,7 @@ static int __init capidrv_init(void)
 
 	errcode = capi20_get_profile(0, &profile);
 	if (errcode != CAPI_NOERROR) {
+		unregister_capictr_notifier(&capictr_nb);
 		capi20_release(&global.ap);
 		return -EIO;
 	}