arm: mvebu: Add RD-AC5X board

arm: mvebu: Add RD-AC5X board

The RD-AC5X-32G16HVG6HLG-A0 development board main components and
features include:
* Main 12V/54V power supply
* 270 Gbps throughput packet processor on the main board
* DDR4:
  * SR1: 2GB DDR4 2400MT/S(1GB x 2 pcs ) with ECC(1GB x 1 pcs)
  * SR2: 4GB DDR4 2400MT/S(2GB x 2 pcs ) with ECC(2GB x 1 pcs)
  * PCB co-layout with 4GB device to support 8GB (Dual CS) requirement
* 16GB eMMC (Samsung KLMAG1JETD-B041006)
* 16MB SPI NOR(GD25Q127C)
* 32 x 1000 Base-T interfaces
* 16 x 2500 Base-T interfaces
  * SR1: 88E2540*4
  * SR2: 88E2580*1+88E2540*2
* Six (6) x 25G Base-R SFP28 interfaces
* One (1) x RJ-45 console connector, interfacing to the on board UART
* One (1) x USB Type-A connector, interfacing to the USB 2.0 port (0)
* One (1) x USB Type-mini B connector, interfacing to the USB 2.0 port (1)
* One (1) x RJ-45 1G Base-T Management port, interfacing to the host
  port (shared with PCIe) Connected to 88E1512 Gigabit Ethernet Phy
* One (1) x Oculink port, interfacing to the PCIe port for external CPU
  connection
* POE 802.3AT support on Port 1 ~ Port 32, 802.3BT support on Port 33 ~
  Port 48 (Microsemi PD69208T4, PD69208M or TI TPS2388,TPS23881
  solution)
* POE total power budget 780W
* LED interfaces per network port/POE
* LED interfaces (common) showing system status
* PTP TC mode Supported (Reserved M.2 connector to support BC mode)

Signed-off-by: Chris Packham <judge.packham@gmail.com>