drm/panel: Read panel orientation for BOE TV101WUM-NL6

This reads the DT setting for the panel rotation to set the panel
orientation in the get_modes callback.

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200813215609.28643-3-digetx@gmail.com