lock: Move disabling DPMS to a function

.config/i3/lock.sh

@@ -14,13 +14,17 @@ lock() {
            --pass-media-keys $@
 }
 
+unsetDPMS() {
+    xset dpms 0 0 0
+}
+
 case "$1" in
     lock)
-        trap "xset dpms 0 0 0" HUP INT TERM
+        trap "unsetDPMS" HUP INT TERM
         # set dpms time to argument, or 0 if none given
         xset +dpms dpms ${2-0} ${2-0} ${2-0}
         lock ${2+"--nofork"}
-        xset dpms 0 0 0
+        unsetDPMS
         ;;
     logout)
         i3-msg exit