gears.color: call the correct creator function in local string_pattern function

The corresponding pattern factory that `string_pattern` delegates to is stored
in the `creator` parameter, and not `v`; probably a typo.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/gears/color.lua.in

@@ -105,7 +105,7 @@ local function string_pattern(creator, arg)
         table.insert(args, v)
     end
     -- And call our creator function with the values
-    local p = v(unpack(args))
+    local p = creator(unpack(args))
 
     add_iterator_stops(p, iterator)
     return p