!13602 Modify MaximumGrad op

From: @ZhengQihao3f3f3f
Reviewed-by: @wuxuejian,@liangchenghui
Signed-off-by: @wuxuejian

mindspore/ccsrc/backend/kernel_compiler/cpu/maximum_grad_cpu_kernel.cc

@@ -63,7 +63,7 @@ void MaximumGradRecTask(T *x, T *y, T *dout, T *dx, T *dy, size_t dim, size_t x_
     size_t dout_i = i * dout_cargo[dim];
 
     if (dim == dout_shape.size() - 1) {
-      if (*(x + x_index + x_i) >= *(y + y_index + y_i)) {
+      if (*(x + x_index + x_i) > *(y + y_index + y_i)) {
         *(dx + x_index + x_i) += *(dout + dout_index + i);
       } else {
         *(dy + y_index + y_i) += *(dout + dout_index + i);