Revert "efi_capsule: Move signature from DTB to .rodata"

This was unfortunately applied despite much discussion about it beiong
the wrong way to implement this feature.

Revert it before too many other things are built on top of it.

This reverts commit ddf67daac39de76d2697d587148f4c2cb768f492.
Signed-off-by: Simon Glass <sjg@chromium.org>
6 files changed