Server Upgrade: Set modified to false, before each update

Variable self.modified should be set to false before each run of update

Ticket: https://fedorahosted.org/freeipa/ticket/3560
Reviewed-By: David Kupka <dkupka@redhat.com>

ipaserver/install/ldapupdate.py

@@ -797,7 +797,7 @@ class LDAPUpdate:
 
         returns True if anything was changed, otherwise False
         """
-
+        self.modified = False
         all_updates = {}
         try:
             self.create_connection()
@@ -841,6 +841,7 @@ class LDAPUpdate:
         Apply updates internally as opposed to from a file.
         updates is a dictionary containing the updates
         """
+        self.modified = False
         if not self.conn:
             self.create_connection()