drm/panel: panel-simple: Add missing pm_runtime_dont_use_autosuspend() calls

The PM Runtime docs specifically call out the need to call
pm_runtime_dont_use_autosuspend() in the remove() callback if
pm_runtime_use_autosuspend() was called in probe():

> Drivers in ->remove() callback should undo the runtime PM changes done
> in ->probe(). Usually this means calling pm_runtime_disable(),
> pm_runtime_dont_use_autosuspend() etc.

We should do this. This fixes a warning splat that I saw when I was
testing out the panel-simple's remove().

Fixes: 3235b0f2 ("drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210517130450.v7.1.I9e947183e95c9bd067c9c1d51208ac6a96385139@changeid