libcommon-cs: move gsm_network_init() into bsc_network_init()

Some part of the network init was common between libbsc and libmsc in the old
openbsc.git repository. Now osmo-bsc.git is independent with its own copy of
the gsm_network initialization. So move it over to libbsc.

Change-Id: I8968787a5f0b078619264f0cb42349a9bc7943af
3 files changed