kea-msg-compiler is only needed if you alter the messages and the
generated sources need to be rebuilt. When this is the case, there are
better ways to build kea-msg-compiler that don't involve building all of
Kea.
Don't depend on kea-native, remove BBCLASSEXTEND=native, and the target
overrides.
Signed-off-by: Ross Burton <ross.burton@arm.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
