target/arm: Convert Data Processing (reg-shifted-reg)

Convert the register shifted by register form of the data
processing insns.  For A32, we cannot yet remove any code
because the legacy decoder intertwines the immediate form.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190904193059.26202-5-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>