dt-bindings: leds: Convert is31fl319x to dtschema

Convert leds-is31fl319x.txt to dtschema.
Set license to the one recommended by DT project
and set myself as maintainer.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220712100841.1538395-2-vincent.knecht@mailoo.org