mvebu: add support for Fortinet FortiWiFi 51E

mvebu: add support for Fortinet FortiWiFi 51E

Fortinet FortiWiFi 51E (FWF-51E) is a UTM with 1x WLAN and 1x SSD, based
on Armada 385 (88F6820).

Specification:

- SoC          : Marvell Armada 385 88F6820
- RAM          : DDR3 2 GiB (4x Micron MT41K512M8DA-107, "D9SGQ")
- Flash        : SPI-NOR 128 MiB (Macronix MX66L1G45GMI-10G)
- SSD          : mSATA SSD 32 GB (A-DATA XM21E (AXM21ES3-32GM-B))
  - mode       : SATA III 6Gbps
  - power      : 3.3 VDC, 3.1 W (Max.)
- Ethernet     : 7x 10/100/1000 Mbps
  - LAN 1-5    : Marvell 88E6176
  - WAN 1, 2   : Marvell 88E1512 (2x)
- WLAN         : Fortinet EMP7618-FT (Atheros AR9382 (2T2R))
  - interface  : MiniPCIe
- LEDs/Keys    : 18x/1x
- UART         : "CONSOLE" port (RJ-45, RS-232C level)
  - port       : ttyS0
  - settings   : 9600bps 8n1
  - assignment : 1:NC , 2:NC , 3:TXD, 4:GND,
                 5:GND, 6:RXD, 7:NC , 8:NC
  - note       : compatible with Cisco console cable
- HW Monitoring: nuvoTon NCT7802Y
- Power        : 12 VDC, 2 A
  - plug       : Molex 5557-02R

Flash instruction using initramfs image:

 1. Power on FWF-51E and interrupt to show bootmenu
 2. Call "[I]: System information." -> "[S]: Set serial port baudrate."
    and set baudrate to 9600 bps
 3. Call "[R]: Review TFTP parameters.", check TFTP parameters and
    connect computer to "Image download port" in the parameters
 4. Prepare TFTP server with the parameters obtained above
 5. Rename OpenWrt initramfs image to "image.out" and put to TFTP
    directory
 6. Call "[T]: Initiate TFTP firmware transfer." to download initramfs
    image from TFTP server
 7. Type "R" key when the following message is showed, to boot initramfs
    image without flashing to spi-nor flash

    "Save as Default firmware/Backup firmware/Run image without saving:[D/B/R]?"

 8. On initramfs image, backup mtd if needed

    minimum:

    - "firmware-info"
    - "kernel"
    - "rootfs"

 9. On initramfs image, upload sysupgrade image to the device and perform
    sysupgrade
10. Wait ~200 seconds to complete flashing and rebooting.
    If the device is booted with stock firmware, login to bootmenu and
    call "[B]: Boot with backup firmware and set as default." to set the
    first OS image as default and boot it.

Notes:

- Both colors of Bi-color LEDs on the front panel cannot be turned on at
  the same time.

- "PWR" and "Logo" LEDs are connected to power source directly.

- The following partitions are added for OpenWrt.
  These partitions are contained in "uboot" partition (0x0-0x1fffff) on
  stock firmware.

  - "firmware-info"
  - "dtb"
  - "u-boot-env"
  - "board-info"

Image header for bootmenu tftp:

  0x0 - 0xf  : ?
 0x10 - 0x2f : Image Name
 0x30 - 0x17f: ?
0x180 - 0x183: Kernel Offset*
0x184 - 0x187: Kernel Length*
0x188 - 0x18b: RootFS Offset (ext2)*
0x18c - 0x18f: RootFS Length (ext2)*
0x190 - 0x193: DTB Offset
0x194 - 0x197: DTB Length
0x198 - 0x19b: Data Offset (jffs2)
0x19c - 0x19f: Data Length (jffs2)
0x1a0 - 0x1ff: ?

*: required for initramfs image

MAC addresses:

(eth0): 90:6C:AC:xx:xx:98 (board-info (OpenWrt), 0xd880 (hex))
WAN 1 : 90:6C:AC:xx:xx:99
WAN 2 : 90:6C:AC:xx:xx:9A
LAN 1 : 90:6C:AC:xx:xx:9B
LAN 2 : 90:6C:AC:xx:xx:9C
LAN 3 : 90:6C:AC:xx:xx:9D
LAN 4 : 90:6C:AC:xx:xx:9E
LAN 5 : 90:6C:AC:xx:xx:9F
WLAN  : 88:DC:96:xx:xx:xx (MiniPCIe Card)

Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>
Tested-by: Raylynn Knight <rayknight@me.com>