NextThing CHIP Pro supported in -current

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Hi folks --

After much waiting, my CHIP Pro arrived yesterday and I added support for 
their GR8 SoC to -current.

Booting is similar to PocketCHIP:

 1. Create a boot script (boot.cmd) with the following contents:

    setenv bootargs 'root=sd0a'
    setenv bootcmd 'fdt addr ${fdt_addr_r}; bootm ${kernel_addr_r} - ${fdt_addr_r}'
    boot

 2. Add a U-Boot header to the boot script, creating boot.scr:

    $ mkubootimage -A arm -C none -O linux -T script -a 0 -n "NetBSD sunxi boot" boot.cmd boot.scr

 3. Install the U-Boot package for the board (sysutils/u-boot-chip-pro).

 4. Install the sunxi-tools package (sysutils/sunxi-tools).

 4. Build a SUNXI kernel from sources after 2017-10-07.

 5. Hold down the FEL button and plug the device into your PC. Using
    the CHIP Pro dev kit, you can use the "USB0 UART" jack for both
    serial console and FEL mode.

    Verify that the device is in FEL mode:

    $ sunxi-fel -l
    USB device 020:024   Allwinner A13     1625420a:504f4159:36333030:08038700

 6. Transfer U-Boot, DTB, and the kernel to the device over USB:

    $ sunxi-fel -p -v \
        uboot /usr/pkg/share/u-boot/chip-pro/u-boot-sunxi-with-spl.bin \
        write 0x42000000 netbsd.ub
        write 0x43000000 sun5i-gr8-chip-pro.dtb \
        write 0x43100000 boot.scr

Have fun!

Jared