misc: Include abis_rsl.h to remove some compiler warnings
This was introduced by a recent change to gsm_data.h to include
less header files. We really need to access the RSL information
here so it is fine to include the file.
diff --git a/openbsc/src/gsm_04_08_utils.c b/openbsc/src/gsm_04_08_utils.c
index 350c69b..b59d710 100644
--- a/openbsc/src/gsm_04_08_utils.c
+++ b/openbsc/src/gsm_04_08_utils.c
@@ -30,6 +30,8 @@
#include <osmocore/msgb.h>
#include <osmocore/gsm48.h>
+
+#include <openbsc/abis_rsl.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_04_08.h>
#include <openbsc/transaction.h>