baremetal: Integrate provisioning and non-provisioning interfaces

Originally, baremetal pxe/tilera driver managed two types of network
interfaces in two tables; provisioning interfaces in bm_nodes table
and non-provisioning (normal) interfaces in bm_interfaces table.
But, now actually both types are handled in the same way and there is
no difference between them except for which table they are in.

This patch moves the provisioning interfaces to bm_interfaces. However
it does not drop prov_mac_address in bm_nodes since VirtualPowerManager
still uses it to identify a target in a list of VMs returned by the
VM's host.

Change-Id: I5ce940e7127aa3b29ba7802612938dc5dbc3152f
Merge "baremetal: Integrate provisioning and non-provisioning interfaces"