ARM: at91/dt: sama5d4: add ISI dt support

Add ISI dt node and pinctrl settings in sama5d4.dtsi.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
[nicolas.ferre@atmel.com: sort nodes in order. remove useless comments]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>