ARM: at91/dt: sama5d4: Add support for DENX MA5D4 SoM and EVK

Add support for the DENX MA5D4 SoM and MA5D4EVK board. The system
consists of a SoM with eMMC, SPI NOR for booting, 2x SPI CAN chip
and an EVK with microSD slot, 2x UART, 2x CAN port, 3x USB port,
LEDs and expansion headers.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>