target/arm: Implement vector shifted SCVF/UCVF for fp16

target/arm: Implement vector shifted SCVF/UCVF for fp16

While we have some of the scalar paths for *CVF for fp16,
we failed to decode the fp16 version of these instructions.

Cc: qemu-stable@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180502221552.3873-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit a6117fae4576edfe7a5a5b802a742c33112c0993)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>