realtek: add support for XikeStor SKS8300-8X

XikeStor (Seeker) SKS8300-8X is a 8 ports Multi-Gig switch, based on
RTL9303.

Specification:

- SoC             : Realtek RTL9303
- RAM             : DDR3 512 MiB
- Flash           : SPI-NOR 32 MiB (Winbond W25Q256JVFIQ)
- Ethernet        : 8x 1/2.5/10 Gbps (SFP+)
- LEDs/Keys (GPIO): 1x/1x
- UART            : "Console" port on the front panel
  - type          : RS-232C
  - connector     : RJ-45
  - settings      : 9600n8
- Watchdog        : Diodes PT7A7514WE
- Power           : 12 VDC, 2 A

Flash instruction using initramfs image:

 1. Prepare TFTP server with an IP address "192.168.2.36"
 2. Connect your PC to Port1 on SKS8300-8X
 3. Power on SKS8300-8X and interrupt by Ctrl + B
 4. Login to the vendor CLI by Ctrl + F and "diagshell_unipoe_env"
 5. Login to the U-Boot CLI by "debug_unish_env" command
 6. Enable Port1 with the following commands

    rtk 10g 0 fiber1g (or fiber10g if 10GBase-*R)
    rtk ext-devInit 0
    rtk ext-pinSet 2 0

    Note: the last command sets tx-disable to low

 7. Download initramfs image from TFTP server

    tftpboot 0x82000000 <image name>

 8. Boot with the downloaded image

    bootm

 9. On the initramfs image, backup the stock firmware if needed
10. Upload (or download) sysupgrade image to the device
11. Erase "firmware" partition to cleanup JFFS2 of stock FW

    mtd erase firmware

12. Perform sysupgrade with the sysupgrade image
13. Wait ~120 sec to complete flashing

Notes:

- A kernel binary "nos.img" needs to be stored into JFFS2 filesystem
  using 4KiB erase block instead of 64KiB.

- PT7A7514WE is handled by hardware-assited system LED output
  (blinking).

MAC addresses:

eth0   : 84:E5:D8:xx:xx:37 (board-info (stock:"flash_raw"), 0x218 (hex))
(ports): 84:E5:D8:xx:xx:36 (board-info (stock:"flash_raw"), 0x1f1 (hex))

Signed-off-by: INAGAKI Hiroshi <[email protected]>

target/linux/realtek/base-files/etc/board.d/02_network

@@ -54,6 +54,9 @@ tplink,t1600g-28ts-v3)
 	label_mac=$(get_mac_label)
 	lan_mac="$label_mac"
 	;;
+xikestor,sks8300-8x)
+	lan_mac=$(mtd_get_mac_binary board-info 0x1f1)
+	;;
 *)
 	lan_mac=$(mtd_get_mac_ascii u-boot-env2 mac_start)
 	lan_mac_end=$(mtd_get_mac_ascii u-boot-env2 mac_end)