kirkwood: add support for Check Point L-50

This patch adds support for the Check Point L-50 from 600/1100 series
routers.

Specification:
-CPU: Marvell Kirkwood 88F6281 1200MHz
-RAM: 512MB
-Flash: NAND 512MB
-WiFi: mPCIe card based on Atheros AR9287 b/g/n
-WAN: 1 Gigabit Port (Marvell 88E1116R PHY)
-LAN: 9 Gigabit Ports (2x Marvell 88E6171(5+4))
-USB: 2x USB2.0
-Express card slot
-SD card slot
-Serial console: RJ-45 115200 8n1
-Unsupported DSL

Known issues:
-DSL not supported
-Expresscard not tested

Installation:

Step one -> backup:
make backup u-boot and env for revert stock posibility
make backup dsl_mac_addr, dmz_mac_addr, eth1addr, ethaddr and all lanX_mac_addr

Step two -> Use kwboot tool to upload openwrt u-boot to RAM:

run kwboot: "kwboot -B 115200 /dev/ttyUSB0 -b u-boot.kwb -p -t"
end start u-boot

Step three -> Restore macs (e.g. below):
setenv eth1addr 00:1C:XX:XX:XX:6C
setenv ethaddr 00:1C:XX:XX:XX:6B
setenv lan1_mac_addr 00:1C:XX:XX:XX:6C
setenv lan2_mac_addr 00:1C:XX:XX:XX:6D
setenv lan3_mac_addr 00:1C:XX:XX:XX:6E
setenv lan4_mac_addr 00:1C:XX:XX:XX:6F
setenv lan5_mac_addr 00:1C:XX:XX:XX:70
setenv lan6_mac_addr 00:1C:XX:XX:XX:71
setenv lan7_mac_addr 00:1C:XX:XX:XX:72
setenv lan8_mac_addr 00:1C:XX:XX:XX:73
setenv dmz_mac_addr 00:1C:XX:XX:XX:74
setenv dsl_mac_addr 00:1C:XX:XX:XX:75

Step four -> flash u-boot:
mw 0x0800000 0xffff 0x100000
nand erase 0x0 100000
tftp 0x0800000 openwrt-kirkwood-l50-u-boot.kwb
nand write 0x0800000 0x0 0x100000
saveenv

Step five -> run initramfs image:

tftpboot 0x02000000 openwrt.bin; bootm 0x02000000;

Step six -> install sysupgrade OpenWrt image:

copy to /tmp/ sysupgrade image
run sysupgrade

Back to stock:
Restore original u-boot end env.
Install factory image via stock u-boot.

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

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

@@ -11,6 +11,9 @@ board_config_update
 board=$(board_name)
 
 case "$board" in
+"checkpoint,l-50")
+	ucidef_set_interfaces_lan_wan "lan1 lan2 lan3 lan4 lan5 lan6 lan7 lan8 dmz" "eth0"
+	;;
 "cisco,on100")
 	ucidef_set_interface_lan "eth0 eth1"
 	;;