We set this for qemu-system-aarch64, but failed to do so
for the strictly 32-bit emulation.

Fixes: 3bec7844 ("target/arm: Provide ARMv8.4-PMU in '-cpu max'")
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>