AUO-K190x: add framebuffer rotation support

Change the driver to use the framebuffer rotation functions to be
able to change the rotation at runtime.

This also removes the setting of the rotation via the platform data.

Signed-off-by: Heiko Stübner <heiko@sntech.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>