Timeout and threshold configurable at run-time

And check if a task is already scheduled when the wake-up arrives, if it
is, don't track this task (fixes the unhandled wakeups).

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
add description of the parameters

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
refactor block_latency to use tracepoints and dynamic parameters

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>