tools lib: Improve clean target

The clean targets miss some .cmd and .d files.

Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kbuild@vger.kernel.org
Link: http://lkml.kernel.org/r/1434631938-12681-1-git-send-email-riku.voipio@linaro.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>