Since commit 27cb7300ff ("Ensure device tree DTS is compiled"),
build succeeds irrespective of the correctness of Makefile.
In fact, you can compile any defconfig without adding any entry in
arch/*/dts/Makefile.
I am going to revert that commit, so device tree must be explicitly
listed in Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
344db3f330