[FS#1140] WNDR4700 - not possible to config/build ( r5227-82a4b8d )

[LEDE Bugs]

The following task has a new comment added:

FS#1140 - WNDR4700 - not possible to config/build ( r5227-82a4b8d )
User who did this - Christian Lamparter (chunkeey)

----------
just revert "build: allow calling append-dtb from image build commands" for now.
----------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1140#comment3758