BSC_Tests: Add TC_chan_exhaustion to test for channel exhaustion

We ensure that all channels are allocated, and that the first allocation
beyond the avialable channels will fail and generate an IMM_ASS_REJ.

WE also verify that the related counters are incremented as expected.

Change-Id: Iade77321588190cec89cfcd9c18d84a7144e0198
1 file changed