Revert "Unset the static $scale variable so a new scale can later be set."

This reverts commit 7aa49b68a4.

See https://github.com/farmOS/farmOS/issues/367

modules/farm/farm_map/farm_map.geo.inc

@@ -46,11 +46,6 @@ function farm_map_set_bcscale($reset = FALSE) {
 
     // Otherwise, reset.
     bcscale($scale);
-
-    // Unset the $scale variable so that a new scale can later be set.
-    // Note that we can't use unset() because this is a static variable.
-    $scale = NULL;
-
     return;
   }