ARM: dts: am335x-sl50: fix label names for all LEDs

Fix the label for all LEDs, we made a mistake setting the label names on
all LEDs, where says green should say red, and viceversa, where says red
should be green.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>