arm64: dts: meson: vim3: correct led polarity

The LEDs on the vim3 are active when the gpio is high, not low.

Fixes: c6d29c66 ("arm64: dts: meson-g12b-khadas-vim3: add initial device-tree")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200803141850.172704-1-jbrunet@baylibre.com