tools: ynl: use uAPI include magic for samples

Makefile.deps provides direct includes in CFLAGS_$(obj).
We just need to rewrite the rules to make use of the extra
flags, no need to hard-include all of tools/include/uapi.

Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20231003153416.2479808-4-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>