Changed the property used to define a layer name for displays from
"label" (which affects other things in Zephyr and is deprecated) to
"display-name". (It cannot be named simply "name", because that has
special meaning in newer versions of the devicetree compiler.)
"label" is still supported as a fallback, so no changes need to be made
to existing keymaps.
* Allows "gaps" for keyboards like Kyra.
* Allows keyboards with matrixes that don't map the logical key
locations to have normal looking keymaps when defined.
