octeon: n821: add Cisco vEdge 1000 base

octeon: n821: add Cisco vEdge 1000 base

This is the first commit to introduce the base for the N821 board used
in Cisco vEdge 1000.

This commit does not include the custom CPLD drivers but rather
everything else that is already present in the upstream kernel.

This results in an image that boots, but e.g. the SFP ports are not
usable.

Hardware:

  - CPU: Cavium Networks CN6130, 4 cores @ 1.0 GHz
  - Flash:
    - 16 MiB SPI NOR presented as 2x8 MiB for A/B boot recovery
    - 8192 MiB eMMC
  - RAM: 4096 MiB
  - Ethernet 1Gbit ports: 1x
  - Ethernet SFP ports: 8x
  - USB ports: 2x 3.0 Type-A on front panel
  - Serial: Two, one internal and one external
  - JTAG: Yes
  - LED count: 18x
  - Button count: 1x
  - GPIOs: 1x
  - Power: 2x redundant DC 12V barrel plug
  - Extra: Slot for SD card on front

See the OpenWrt wiki for more hardware details.

Installation:

  - Flash squashfs to /dev/sda2 and put kernel on /dev/sda1.
  - Update uboot's bootcmd environment variable to match.

Full installation guide will be added to OpenWrt wiki when sysupgrade
support is added.

Signed-off-by: Christian Svensson <blue@cmd.nu>
Signed-off-by: Tommy Nevtelen <tommy@nevtelen.com>
Tested-by: Viktor Ekmark <viktor@ekmark.se>
Tested-by: Daniel Wennberg <github@networkninja.se>