ARM: dts: da850: add vpif video display pins

Add a new pinctrl sub-node for vpif display pins. Move VP_CLKIN3 and
VP_CLKIN2 to the display node where they actually belong (vide section
36.2.2 of the OMAP-L138 technical reference manual).

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>