bridge: Set ofport column in every database transaction.

bridge: Set ofport column in every database transaction.

Database transactions can occasionally fail due to concurrent changes in
the database.  When that happens, the next transaction should repeat the
changes that ovs-vswitchd tried to make the first time (adjusted for the
changes to the database).

The code to report the OpenFlow port number in use didn't do that.  It set
the ofport field once when it created the port and never set it again, even
if the transaction to set it failed.  This commit fixes the problem.

Bug #23047.
Reported-by: Suganya Ramachandran <suganyar@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Justin Pettit <jpettit@nicira.com>