kirkwood: add support for two clones from Endian

kirkwood: add support for two clones from Endian

They are Endian 4i Edge 200 and his clone Endian UTM Mini.

Hardware:
  - SoC: Marvell 88F6281-A1 ARMv5TE Processor 1.2GHz
  - Ram: 512MB (4x Nanya NT5TU128M8GE-AC)
  - NAND Flash: 512MB (Micron 29F4G08AAC)
  - Lan 1-4: 4x GBE (Marvell 88E6171R-TFJ2)
  - Lan 5: 1x GBE (Marvell 88E1116R-NNC1)
  - Storage: MicroSD Slot
  - WLAN: MiniPCIe Slot present, and fitted with SparkLan WPEA-110N/E
          (Atheros AR9280 chipset) (ONLY Endian UTM Mini WLAN)
  - USB: 1x USB 2.0 port
  - Console: RJ-45 port
  - LEDs: 3x GPIO controlled

Notes:
  - WLAN led (Endian UTM Mini) is drived by MPCIE card

Installation by TFTP + serial:
  - Setup TFTP server and copy initramfs image
  - Connect serial console
  - Stop booting in u-boot
  - Do:
	setenv bootargs 'console=ttyS0,115200n8 earlyprintk'
	saveenv
	setenv serverip 192.168.1.1
	setenv ipaddr 192.168.1.2
	tftpboot 0x1200000 openwrt-kirkwood-endian_4i-edge-200-initramfs-uImage
	bootm 0x1200000
  - copy sysupgrade image via ssh.
  - run sysupgrade

Installation by USB + serial:
  - Copy initramfs image to fat32 usb drive
  - Connect pendrive to USB 2.0 front socket
  - Connect serial console
  - Stop booting in u-boot
  - Do:
	setenv bootargs 'console=ttyS0,115200n8 earlyprintk'
        saveenv
	usb reset
	fatload usb 0:1 0x1200000 openwrt-kirkwood-endian_4i-edge-200-initramfs-uImage
	bootm 0x1200000
  - copy sysupgrade image via ssh.
  - run sysupgrade

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>