target/arm: Replace ARM_FEATURE_VFP4 with isar_feature_aa32_simdfmac

target/arm: Replace ARM_FEATURE_VFP4 with isar_feature_aa32_simdfmac

All remaining tests for VFP4 are for fused multiply-add insns.

Since the MVFR1 field is used for both VFP and NEON, move its adjustment
from the !has_neon block to the (!has_vfp && !has_neon) block.

Test for vfp of the appropraite width alongside the test for simdfmac
within translate-vfp.inc.c.  Within disas_neon_data_insn, we have
already tested for ARM_FEATURE_NEON.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200224222232.13807-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>