target/arm: Enable FEAT_MOPS for CPU 'max'

Enable FEAT_MOPS on the AArch64 'max' CPU, and add it to
the list of features we implement.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-13-peter.maydell@linaro.org