main: copy u-boot files to working directory
U-boot files may be used to generate boot images during boot-deploy stage, for example u-boot's FIT images, android boot images. If there's no u-boot directory for device, skip copying.
deviceinfo: add Boardname
Alpine u-boot package places board files in separate directories, /usr/share/u-boot/$boardname. This param specifies device u-boot subdirectory.
Edited by Administrator