Bluetooth: controller: Prevent incorrect lazy_current increment

Prevent redundant collision resolves and potential incorrect and harmful
increment of lazy_current.

During collision scenarios with high CPU load, the ticker_worker may be
called a second time before the ticker_job gets to run. This will cause
ticker operations on the previosly expired node (expected), and in some
cases increment lazy_current, even though the node was not sceduled to
execute via the req/ack mechanism.

By moving the request check before collision resolve, CPU time is saved,
and lazy_current will not incorrectly be incremented if node is in
collision.

The problem may be seen as a connection suddenly not receiving packets,
or MIC error on master, because the event counter goes out of sync.

Signed-off-by: Morten Priess <mtpr@oticon.com>