ARM: at91: dts: sama5d3: split isi pinctrl

As the ISI has 12 data lines, however we only use 8 data lines with
sensor module. So, split the data line into two groups which make
it can be choosed depends on the hardware design.

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