move to libcommon-cs: net init 2: move bsc_network_init decl to new .h

bsc_network_init() is more fit to live in a BSC specific header, move it to new
common_bsc.h. It will probably also absorb the BSC-specific part of gsm_network
in the future.

Adjust header includes across the board. Particularly, fix abis_nm.h by
explicitly including gsm_data.h: it so far relied on other headers to do that,
which now is no longer always given.

Change-Id: I9edfb1e748bb1cb484fadd48b0406f5b3098e89b
diff --git a/openbsc/src/ipaccess/ipaccess-config.c b/openbsc/src/ipaccess/ipaccess-config.c
index 06589f7..1ef8e3e 100644
--- a/openbsc/src/ipaccess/ipaccess-config.c
+++ b/openbsc/src/ipaccess/ipaccess-config.c
@@ -38,7 +38,7 @@
 #include <osmocom/core/select.h>
 #include <osmocom/core/timer.h>
 #include <openbsc/ipaccess.h>
-#include <openbsc/gsm_data.h>
+#include <openbsc/common_bsc.h>
 #include <osmocom/abis/e1_input.h>
 #include <openbsc/abis_nm.h>
 #include <openbsc/signal.h>