target/arm: Convert barrier insns to decodetree

Convert the insns in the "Barriers" instruction class to
decodetree: CLREX, DSB, DMB, ISB and SB.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230602155223.2040685-4-peter.maydell@linaro.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
2 files changed