nimble/controller: Fix disconnection event status
nimble/controller: Fix disconnection event status

If connection is disconnected because it has not been established,
error code 0x3e should be used.

X-Original-Commit: 72a3b9f034ac756d4688327b0a20e5c38b0105d8

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble