target/arm: Correct VMOV_imm_dp handling of short vectors

Coverity points out (CID 1402195) that the loop in trans_VMOV_imm_dp()
that iterates over the destination registers in a short-vector VMOV
accidentally throws away the returned updated register number
from vfp_advance_dreg(). Add the missing assignment. (We got this
correct in trans_VMOV_imm_sp().)

Fixes: 18cf951
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190702105115.9465-1-peter.maydell@linaro.org

target/arm/translate-vfp.inc.c

@@ -1971,7 +1971,7 @@ static bool trans_VMOV_imm_dp(DisasContext *s, arg_VMOV_imm_dp *a)
 
         /* Set up the operands for the next iteration */
         veclen--;
-        vfp_advance_dreg(vd, delta_d);
+        vd = vfp_advance_dreg(vd, delta_d);
     }
 
     tcg_temp_free_i64(fd);