Insist on kernel 3.2.0-69 for precise

Kernel 3.2.0-70 breaks openvswitch compilation on precise,
this removes -70 and reinstalls -69 so that it continues
working. Ubuntu bug is at
https://bugs.launchpad.net/ubuntu/+source/openvswitch/+bug/1379201

Change-Id: I3f854cc662652606669920367b4ff4cc4d545f88