cosmetic: rename subscr_conn_from to complete_layer3_type

'subscr_conn_from' could mean anything: from what, RAN type? BSS identifier? MM
action? Clearly name it as the Complete Layer 3 kind it represents.

Related: OS#3122
Change-Id: I6263a80e6db01c2ca48df6c58b05e2fd19347057
3 files changed