target/arm: Convert BRA[AB]Z, BLR[AB]Z, RETA[AB] to decodetree

Convert the single-register pointer-authentication variants of BR,
BLR, RET to decodetree. (BRAA/BLRAA are in a different branch of
the legacy decoder and will be dealt with in the next commit.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230512144106.3608981-19-peter.maydell@linaro.org
2 files changed