lsc: set the -mout argument to 0 instead of "" by default (meaning None)

It seems for some reason, MOUT is not set to 0 sometimes in the
lakeshore 336. Make this explicit.

tcl/drivers/lsc.tcl

@@ -4088,7 +4088,7 @@ proc stdConfig::lsc_loop args {
   variable lsc_kinkscale
 
   scanargs $args var -relpath -channel -maxheater -resist -loop 1 \
-    -linearpower 0 -color auto -loopname "" -mout "" -is 0
+    -linearpower 0 -color auto -loopname "" -mout 0 -is 0
 
   node $relpath wr
   default 0