arm64: dts: Add Librem5 Evergreen

Add librem5-r4 with specifics to that revision like the near-level,
battery and charger properties. For schematics and more information,
see https://developer.puri.sm/Librem5/Hardware_Reference/Evergreen.html



Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>