Changes from purism:
- 2 second boot delay removed
- This includes an updated DDR memory training firmware version.
- patch to work around wifi device not being available on boot
Package changes:
- u-boot installed in location consistent with other pmaports/u-boot
packages
- update-u-boot script added for upgrading u-boot on the device
- devkit u-boot split off into a sep. subpackage
