Maple trees have very thin bark and splitting is quite common.  You can wrap the trees for additional winter protection.  See the website: https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter

The white areas are visible but I cannot enlarge them enough to identify it.  It could be fungi, scale or even lichen. Could you send a closeup?  See: 

http://apps.extension.umn.edu/garden/diagnose/plant/deciduous/maple/

An onsite inspection by a certified tree professional may also help identify the white areas and also help to determine if the split needs trimming to prevent invasion by insects and fungi. See:  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional

Below is a close up photo of the “white stuff” in the split areas of the bark on my maple tree.  What is it?

These appear to be shelf fungi.  They are an indication of sapwood rot.  If this is a high value tree, a tree professional is needed to do an onsite inspection and determine the extent of damage under the bark.  See:  

1.  https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/maple/branchesfungi.html2.  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional