bsc: Move gsm_network_init function to libbsc

Currently libcommon depends on libbsc, because gsm_network_init
(libcommon/gsm_data.c) directly calls gsm_net_update_ctype
(libbsc/gsm_04_08_utils.c).

This patch moves gsm_network_init to a new file libbsc/net_init.c.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/libbsc/Makefile.am b/openbsc/src/libbsc/Makefile.am
index 0c22662..3588b66 100644
--- a/openbsc/src/libbsc/Makefile.am
+++ b/openbsc/src/libbsc/Makefile.am
@@ -23,5 +23,6 @@
 			gsm_04_08_utils.c \
 			bsc_init.c bts_init.c bsc_rf_ctrl.c \
 			arfcn_range_encode.c bsc_ctrl_commands.c \
-			bsc_ctrl_lookup.c
+			bsc_ctrl_lookup.c \
+			net_init.c