In before, the scheduler makes decisions based on CONF.enable_cpu_pinning
in controller node. Toggle this config in controller node will either
turn on/off cpu pinning for *all* compute nodes. This commit fixes it
by reading enable_cpu_pinning from the database table.
As a result, individual compute node can turn on/off cpu pinning.
Change-Id: I466562138205d11054d3bc428247116160f337c8