kvm tools: Enable PPC64 to build static

By "enable", I mean "fix"; the re-jigged commit 7ef85e8b builds libfdt
using OBJS rather than OTHEROBJS hence ignores the relaxed CFLAGS.

This commit builds it via OTHEROBJS.

Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>