arm64: dts: imx8mq-librem5: Fix led_r and led_g pinctrl assignments

Fix wrong pinctrl assignments.

Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Suggested-by: Eric Kuzmenko <eric.kuzmenko@puri.sm>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>