hikey: Use common rules for TAs etc

It seems like there where some leftovers from the consolidation of the
filesystem generation patches a while ago. This cleans up duplicates
etc and fixes an error when generating the root fs due to recent
changes.

Signed-off-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Reviewed by: Victor Chong <victor.chong@linaro.org>