target/arm: Define syndrome function for MOPS exceptions

target/arm: Define syndrome function for MOPS exceptions

The FEAT_MOPS memory operations can raise a Memory Copy or Memory Set
exception if a copy or set instruction is executed when the CPU
register state is not correct for that instruction. Define the
usual syn_* function that constructs the syndrome register value
for these exceptions.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-5-peter.maydell@linaro.org