ARM: at91: dts: sama5d3: add ov2640 camera sensor support

According to v4l2 dt document, we add:
  a camera host: ISI port.
  a i2c camera sensor: ov2640 port.
to sama5d3xmb.dtsi.

The ov2640 node defines the pinctrls, clocks and refer to isi port.
The ISI node also has a reference to the ov2640 port.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>