target/arm: Use fp_status_fp16 for do_fmpa_zpzzz_h

target/arm: Use fp_status_fp16 for do_fmpa_zpzzz_h

This makes float16_muladd correctly use FZ16 not FZ.

Fixes: 6ceabaad110
Cc: qemu-stable@nongnu.org (3.0.1)
Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Message-id: 20180810193129.1556-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 52a339b11d1719a6589de40606859939875fda9a)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>