This code will get _really_ repetive, and we'll end up with tons more
of this kind. So extract the common patterns.

This should also help when we add a lazy pipe_config compare mode for
fastboot.
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>