Try this:
1. Create blank layer with Mode set to Color Burn, and fill with white.
2. Set Foreground color to black, and select a soft brush with Opacity 3 to 5 %.
3. Click or brush over the haze areas slowly building up density.
4. Adjust the opacity of the layer as needed.
Here is before-after. I initially brushed over the entire picture, but then did more on the hill and trees where the haze was more noticeable.
