Fix ML2 VXLAN TypeDriver DB migration

The migration for the ML2 VXLAN TypeDriver was incorrectly setting
primary key attributes on separate lines for 'ip_address' and
'udp_port'. Also, a primary key cannot have autoincrement set, so
add this to 'udp_port' as well.

Fixes bug 1213134

Change-Id: I0b2e2685bf524dd9c0333ac4511287ad6a5eb87e
Merge "Fix ML2 VXLAN TypeDriver DB migration"