fix database request on root cmd

Author: siscia

daemon/cmd/root.go

@@ -8,10 +8,6 @@ import (
 	"github.com/cvmfs/docker-graphdriver/daemon/lib"
 )
 
-func init() {
-	rootCmd.PersistentFlags().StringVarP(&lib.DatabaseLocation, "database", "d", lib.DefaultDatabaseLocation, "database location")
-}
-
 var rootCmd = &cobra.Command{
 	Use:   "daemon",
 	Short: "Show the several commands available.",