MAX_NODE_NAME_LEN limit incorrectly applies to both node-name and unit-address

[oswin5656]

Section 2.2.1.1 of the Device Tree Specification (https://devicetree-specification.readthedocs.io/en/v0.3/devicetree-basics.html) says that:

Each node in the devicetree is named according to the following convention:

node-name@unit-address

The node-name component specifies the name of the node. It shall be 1 to 31 characters in length and consist solely of characters from the set of characters in Table 2.1.

However, this package limits the full "node-name@unit-address" together to 31 characters, causing otherwise valid device trees to fail to parse.