ARM: remove bit-rotten STANDALONE_DEBUG for decompressor

I tried to get this running to debug the regression introduced by
e7db7b42 without success.  But this has several problems that make it
hard to fix:

  - lib/decompress_inflate.c includes in-kernel headers that make
    it difficult to compile for user space.
  - the binary formats changed both in kernel and user space and
    at least for the kernel side there isn't only a single
    variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>