libnetwork: Controller: remove mutex for "store"

The store field is only mutated by Controller.initStores(), which is
only called inside the cosntructor (libnetwork.New), so there should be
no need to protect the field with a mutex in non-exported functions.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/store.go

@@ -11,9 +11,6 @@ import (
 )
 
 func (c *Controller) initStores() error {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
 	if c.cfg == nil {
 		return nil
 	}
@@ -34,9 +31,6 @@ func (c *Controller) closeStores() {
 }
 
 func (c *Controller) getStore() *datastore.Store {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
 	return c.store
 }