bsc_msc: Remove use_count from the subscriber connection

A channel will be released in case of
    * Errors via the clear_request callback...
    * no more transactions and operations are going on.

This means that if we do something without a transaction
the channel might be closed down right away. The bug fix
will be to create a transaction/operation.
diff --git a/openbsc/doc/channel_release.txt b/openbsc/doc/channel_release.txt
index bacf09c..a10e9d5 100644
--- a/openbsc/doc/channel_release.txt
+++ b/openbsc/doc/channel_release.txt
@@ -31,6 +31,8 @@
 
 == Implementation in OpenBSC ==
 
+THIS IS OUTDATED and will be updated...
+
 chan_alloc.c:lchan_auto_release()
 	* checks if use count still > 0 (abort)
 	* calls gsm48_send_rr_release()