SGSN_Tests: Make f_gmm_attach() and f_gmm_auth() work on gb_idx != 0

Let's make sure the related functions can be used on other gb_idx,
i.e. via another Gb interface (and hence simulated RAN/PCU) than
the first one.

Change-Id: Ie88cbf0c70269cc3e2c2fd2a0c65c8f2130ec2b1
1 file changed