a_reset: cleanup + remove dead code

a_reset.c/h was originally developed to be used in both, bsc and
msc without changes. Unfortunately no suitable library has been
found for a_reset.c/h so the file ended up as duplicated code in
both split brances. Eventually we decided to specialize the
generalized code again, which means some of the functions needed
only by osmo-bsc are removed.

- Remove dead code
- Fix timer identification number (T16)
- use fi->priv to hold context info
- Minor cosmetic fixes

Change-Id: I8e489eb494d358d130e51cb2167929edeaa12e92
Depends: libosmocore I36d221c973d3890721ef1d376fb9be82c4311378
Related: OS#3103
diff --git a/include/osmocom/msc/a_iface.h b/include/osmocom/msc/a_iface.h
index 3098b51..217011d 100644
--- a/include/osmocom/msc/a_iface.h
+++ b/include/osmocom/msc/a_iface.h
@@ -51,7 +51,7 @@
 	/* A pointer to the reset handler FSM, the
 	 * state machine is allocated when the BSC
 	 * is registerd. */
-	struct a_reset_ctx *reset;
+	struct osmo_fsm_inst *reset_fsm;
 
 	/* A pointer to the sccp_user that is associated
 	 * with the A interface. We need this information