Add aml8726-m3 config files

[john-feith.com]

Summary

This adds config files for an aml8726-m3 based device.

Test Plan

Tested on Yiyate Android TV Box (aml8726-m3) by doing:

tv open 480p
mmc rescan 0
fatload mmc 0 0x80100000 kernel.bin
go 0x80100000

The current FreeBSD driver doesn't program the video clocks so the u-boot
tv command is necessary in order for the frame buffer to be useful (otherwise
it can be skipped).

The SD card for the Yiyate Android TV Box doesn't need anything special
beyond creating a FAT16 and a UFS filesystem.