target/arm: Don't change pauth features when changing algorithm

target/arm: Don't change pauth features when changing algorithm

We have cpu properties to adjust the pauth algorithm for the
purpose of speed of emulation.  Retain the set of pauth features
supported by the cpu even as the algorithm changes.

This already affects the neoverse-v1 cpu, which has FEAT_EPAC.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230829232335.965414-5-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>