Before using softmmu page tables for the ptw, plumb down
a debug parameter so that we can query page table entries
from gdbstub without modifying cpu state.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20221011031911.2408754-9-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>