csky: remove builtin-dtb Kbuild

Remove the builtin-dtb implementation in arch/csky.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
3 files changed