These bits become writable with the ARMv8.3-PAuth extension.
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20190129143511.12311-1-richard.henderson@linaro.org
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>