target-arm: aarch64: add support for 1-src data processing and CLZ

this patch adds support for decoding 1-src data processing insns,
and the first user, C5.6.40 CLZ(count leading zeroes).

Signed-off-by: Alexander Graf <agraf@suse.de>

[claudio: adapted to new decoder, simpler path for 64bit form,
          reuse 32bit helper for 32bit form]

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>

From Alexander Graf <agraf@suse.de> aarch64 series 47/60