target-arm: A64: add support for floating point compare

this adds decoding support for C3.6.22 Floating-point compare

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
target-arm: A64: add support for floating point conditional compare

this adds decoding support for C3.6.23 FP Conditional Compare

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>