Fix checkstyle

Author: Fabricio Duarte

server/src/main/java/com/cloud/deploy/DeploymentPlanningManagerImpl.java

@@ -20,7 +20,6 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;