ARM: davinci: da8xx-dt: add OF_DEV_AUXDATA entry for lcdc

This is required for tilcdc to be able to acquire a functional clock
on da850 SoCs.

Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
[Bartosz:
  - added the commit description
  - changed the compatible string to 'ti,da850-tilcdc']
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>