build : provide FRU yaml as configurable input

In preparation for the openpower-vpd-parser recipe, make it possible to
provide the FRU data YAML file as a build-configurable input.

Use writefru.yaml as default.

Change-Id: I32dba99bcb6c8dd4da259f907b0499b3192cc412
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
3 files changed