target/arm: Implement FEAT_HPDS2 as a no-op

target/arm: Implement FEAT_HPDS2 as a no-op

This feature allows the operating system to set TCR_ELx.HWU*
to allow the implementation to use the PBHA bits from the
block and page descriptors for for IMPLEMENTATION DEFINED
purposes.  Since QEMU has no need to use these bits, we may
simply ignore them.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20230811214031.171020-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>