target/arm: Convert Neon one-register-and-immediate insns to decodetree

target/arm: Convert Neon one-register-and-immediate insns to decodetree

Convert the insns in the one-register-and-immediate group to decodetree.

In the new decode, our asimd_imm_const() function returns a 64-bit value
rather than a 32-bit one, which means we don't need to treat cmode=14 op=1
as a special case in the decoder (it is the only encoding where the two
halves of the 64-bit value are different).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200522145520.6778-10-peter.maydell@linaro.org