When dumping a guest with dump-guest-memory also dump the SVE
registers if they are in use.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200120101832.18781-1-drjones@redhat.com
[PMM: fixed checkpatch nits]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>