libxl: remove redundant info from dm info.

libxl: remove redundant info from dm info.

Remove "target_ram", "acpi", "vcpus" and "vcpu_avail" from device model info
and use domain_build_info instead. These must all be consistently specified to
both the domain and the device model, there is no need (and a great deal of
danger) in exposing a way for a user of libxl to set them differently.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>