Barosim: Simplify to a plain loop without reschedules or sub interfaces. Behaves now. The DriverFramework needs closer inspection for busy-running threads.

Driver framework

Previously, pointer to an uninitialized int was being passed as the
instance pointer. Now we pass a NULL pointer instead and the code
being called will use the default instance value of zero.

Make sure `struct position_estimator_inav_params params` is properly initialized.

At first there was no indication that this struct was un-initialized because valgrind
was issuing warnings about values that were derived (via float calculations) from
values in this struct. Maybe instruction re-ordering during optimization caused
this disconnect between the source of the problem and the symptom.

Two uninitialized data fixes

The `orb_check` function takes a pointer to a `bool` which it then passes
to `px4_ioctl`. However, if the call to `px4_ioctl` fails, the bool
doesn't get updated (neither set nor cleared). Therefore, in `orb_check`
we explicitly set the bool to `false` before passing the pointer to
`px4_ioctl`.

During construction of an Navigator object, a pointer to the incomplete
object was passed to the RTL constructor which then called a method on
the incomplete Navigator object accessing uninitialized data.

DriverFramework was updated to properly delete nodes in managed lists.

Baro was fixed to use DriverFramework.

Accelsim was fixed with change to DriverFramework to return < 0 when start()
is called and the driver was already started, or stop() is called but the
driver was not running.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>