mgcp: add missing switch case

In the beginning of the CRCX phase for the network does not distinguish
between EV_MDCX_BTS_RES and EV_TEARDOWN, so a Teardown due to an error
could be misinterpreted as a successful MGW response.

Add missing case statement to distinguish CV_MDCX_BTS_RES from
EV_TEARDOWN.

Change-Id: I9bf49df167d94b33ad65d8b9382a01f160b5aec0
1 file changed