sxmo_wm.sh: fix dpms switch when outputs are partially turned off

In a situation of one output was already turned off manualy by the user,
the script was not turning off other outputs.

Reversing this check produce a more consistent behavior.

Signed-off-by: Willow Barraco <contact@willowbarraco.fr>
Signed-off-by: Anjandev Momi <anjan@momi.ca>

scripts/core/sxmo_wm.sh

@@ -25,9 +25,9 @@ xorgdpms() {
 
 swaydpms() {
 	STATE=off
-	if swaymsg -t get_outputs \
+	if ! swaymsg -t get_outputs \
 		| jq ".[] | .dpms" \
-		| grep -q "false"; then
+		| grep -q "true"; then
 		STATE=on
 	fi