From what I can tell it seems that kernels without this patch will try and use this memory even if it is marked in the device-tree as status="disabled" which could lead to problems for older kernels when we start exporting this property from firmware.
Arguably this might not be such a problem in practice as we probably don't have many (if any) existing kernels that will boot on hardware exporting these properties.
However given this patch seems fairly independent perhaps it is worth sending as a separate fix if it is not going to make it into this release?