nimble/ll: Fix race on create connection
nimble/ll: Fix race on create connection

If AUX_CONNECT_RSP is invalid we should immediately remove connection
from scheduler, then we can do other stuff. In other case, we may be
a bit too late and scheduler will fire already scheduled connection
event for a connection that is not created.

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