Baremetal PXE driver should read deploy_kernel_id & deploy_ramdisk_id
from the 'baremetal:' namespace within instance_type['extra_specs']
so that it doesn't conflict with ComputeCapabilitiesFilter any more.
This allows nova-compute to use ComputeCapabilitiesFilter with baremetal
again. For this filter to properly match the baremetal ndoe's RAM,
we need to tune two other Nova options for physical hardware.
Fixes bug 1129485.
Change-Id: I0aa1b0fef8ac59a06217577af8c747437d2d6bf5