!12953 Fix second grad output of BCEWithLogicLoss.

From: @liu_xiao_93
Reviewed-by: @liangchenghui,@wuxuejian
Signed-off-by: @liangchenghui

mindspore/ops/_grad/grad_nn_ops.py

@@ -1090,19 +1090,25 @@ def get_bprop_ce_with_logits_loss(self):
     add = P.Add()
     sub = P.Sub()
     size = P.Size()
+    neg = P.Neg()
+    log = P.Log()
 
     def bprop(predict, target, weight, pos_weight, out, dout):
         sigmoid_input = sigmoid(predict)
         if pos_weight is not None:
             t = mul(target, pos_weight)
             dx = mul(sub(mul(sub(add(t, 1), target), sigmoid_input), t), dout)
+            grad_target = mul(sub(log(sub(1, sigmoid_input)), mul(pos_weight, log(sigmoid_input))), dout)
         else:
             dx = mul((sigmoid_input - target), dout)
+            grad_target = mul(predict, neg(dout))
         if weight is not None:
             dx = mul(dx, weight)
+            grad_target = mul(grad_target, weight)
         if reduction == 'mean':
             dx = dx / size(dx)
-        return dx, zeros_like(target), zeros_like(weight), zeros_like(pos_weight)
+            grad_target = grad_target / size(target)
+        return dx, grad_target, zeros_like(weight), zeros_like(pos_weight)
 
     return bprop