Add u-boot-orangepi-pc 2018.11.

Packaged by kikadf in wip and in PR pkg/54704

U-Boot is a bootloader for embedded boards based on PowerPC, ARM, MIPS and
several other processors, which can be installed in a boot ROM and used to
initialize and test the hardware or to download and run application code.

This package provides U-Boot for the Xunlong Orange Pi PC.

(maya)