Orange Pi Zero support

[Johnny Sorocil]

I have built -CURRENT (63fd4c37fb976e1c00408fd95f168af12088f92b) but I am
unable to boot the board with sun8i-h2-plus-orangepi-zero.dtb (there is
nothing on serial console).
If sun8i-h3-orangepi-one.dtb is loaded, then board boots normally.

Steps to reproduce:
rm -rf /usr/obj
make -j4 TARGET_ARCH=armv6 SRCCONF=/dev/null __MAKE_CONF=/dev/null
buildworld
make -j4 TARGET_ARCH=armv6 SRCCONF=/dev/null __MAKE_CONF=/dev/null
KERNCONF=ALLWINNER buildkernel
make -j4 TARGET_ARCH=armv6 SRCCONF=/dev/null __MAKE_CONF=/dev/null
KERNCONF=ALLWINNER DESTDIR=/mnt/sd2/ installkernel
make -j4 TARGET_ARCH=armv6 SRCCONF=/dev/null __MAKE_CONF=/dev/null
KERNCONF=ALLWINNER DESTDIR=/mnt/sd2/ installworld
cp -f /usr/obj/arm.armv6/usr/src/sys/boot/arm/uboot/ubldr{,.bin} /mnt/sd1
umount /mnt/sd1 ; umount /mnt/sd2
dd if=/usr/local/share/u-boot/u-boot-orangepi-one/u-boot-sunxi-with-spl.bin
conv=notrunc,sync of=/dev/mmcsd0 bs=1024 seek=8

  loader> load -t dtb sun8i-h2-plus-orangepi-zero.dtb
  loader> boot
  Booting...
  Using DTB from loaded file '/boot/dtb/sun8i-h2-plus-orangepi-zero.dtb'.
  Kernel entry at 0x42200100...
  Kernel args: (null)
and it will hang

If H3 dtb file is used:
loader> load -t dtb sun8i-h3-orangepi-one.dtb
loader> boot
Booting...

Using DTB from loaded file
'/boot/dtb/sun8i-h3-orangepi-one.dtb'.

Kernel entry at
0x42200100...

Kernel args:
(null)

KDB: debugger backends:
ddb

KDB: current backend:
ddb

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FreeBSD 12.0-CURRENT #0 63fd4c37fb9(master): Sun Jun 25 12:03:35 CEST
2017
    root at innovator:/usr/obj/arm.armv6/usr/src/sys/ALLWINNER
arm

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