dt-bindings: leds-mt6360: Drop redundant 'unevaluatedProperties'

The binding has both 'unevaluatedProperties: false' and
'additionalProperties: false' which is redundant. 'additionalProperties'
is the stricter of the two, so drop 'unevaluatedProperties'.

Fixes: e05cab34 ("dt-bindings: leds: Add bindings for MT6360 LED")
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220426133508.1849580-1-robh@kernel.org