cosmetic: rename bsc_api.h to gsm_08_08.h

See also I91922f557072d0fb8cfe213a8a7b50f3bb23dea0, which renames
osmo_bsc_api.c to gsm_08_08.c.

Change-Id: I7179eb27183ee213f8fc8d548895b67aa43dc6a2
diff --git a/include/osmocom/bsc/Makefile.am b/include/osmocom/bsc/Makefile.am
index 57837ec..02a4ad8 100644
--- a/include/osmocom/bsc/Makefile.am
+++ b/include/osmocom/bsc/Makefile.am
@@ -54,7 +54,7 @@
 	timeslot_fsm.h \
 	ussd.h \
 	vty.h \
-	bsc_api.h \
+	gsm_08_08.h \
 	penalty_timers.h \
 	osmo_bsc_lcls.h \
 	$(NULL)