HO: move penalty timers to own file as proper API

Separate penalty timers API from specific struct members and move to own .h/.c
file, so that future code may re-use the API arbitrarily.

Change-Id: Ife975a1c7c17a500b1693be620475a8bea72f86f
diff --git a/include/osmocom/bsc/Makefile.am b/include/osmocom/bsc/Makefile.am
index b996070..9247119 100644
--- a/include/osmocom/bsc/Makefile.am
+++ b/include/osmocom/bsc/Makefile.am
@@ -49,4 +49,5 @@
 	ussd.h \
 	vty.h \
 	bsc_api.h \
+	penalty_timers.h \
 	$(NULL)