ARM: at91/dt: sama5d3 xplained: disable pmic

As PMIC act8865 can disturb communication on i2c1, and as it should be setup
correctly then its i2c interface disabled by bootloader, we simply disregard it
in DT.

Acked-by: Wenyou Yang <wenyou.yang@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>