ARM: dts: da850: rename the display node label

The tilcdc node name is 'display' as per the ePAPR 1.1 recommendation.
The label is also 'display', but change it to 'lcdc' to make it clear
what the underlying hardware is.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>