at91: add support for sama5d2 icp board

at91: add support for sama5d2 icp board

Add support for SAMA5D2 ICP board.

Hardware:
- SoC: SAMA5D27
- RAM: 512 MB DDR3L
- MMC: One stanard SD card interface
- USB: One USB host switch 4 ports with power switch,
       One USB device type Micro-AB
- CAN: 2 interfaces
- Ethernet: One Gigabit Ethernet PHY through HSIC,
	    One ETH switchport,
	    One EtherCAT interface
- WiFi/BT: Footprint for IEEE 802.11 b/g/n Wi-Fi plus
	   Bluetooth module (Wi-Fi/BT), suitable for
	   Microchip WILC3000-MR110CA or WILC3000-MR110UA
- Debug port: One J-Link-OB/J-Link-CDC, one JTAG interface
- Leds: one RGB LED
- Buttons: reset, wakeup, 2 user buttons
- Expansion: one PIOBU/PIO connector, 3 mikrobus sockets
- Power mangament: PMIC (MCP16502), one power consumption device
                   (PAC1934)

Not working in Linux:
- EtherCAT interface: there is no Linux support integrated
- PAC1934: driver available at [1] but not integrated in Linux

Flashing:
- follow the procedure at [2]

[1] https://ww1.microchip.com/downloads/en/DeviceDoc/pac193x_linux_driver.zip
[2] https://www.linux4sam.org/bin/view/Linux4SAM/Sama5d2IcpMainPage#Create_a_SD_card_with_the_demo

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>