For Intel and PowerPC the implementation is calling a cpu driver
function across driver layers (i.e. from qemu driver directly to cpu
driver).
The correct behavior is to use libvirt API functionality to perform such
a inter-driver call.

This patch introduces a new cpu driver API function getModels() to
retrieve the cpu models. The currect implementation to process the
cpu_map XML content is transferred to the INTEL and PowerPC cpu driver
specific API functions.
Additionally processing the cpu_map XML file is not safe due to the fact
that the cpu map does not exist for all architectures. Therefore it is
better to encapsulate the processing in the architecture specific cpu
drivers.
Signed-off-by: NDaniel Hansel <daniel.hansel@linux.vnet.ibm.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.vnet.ibm.com>
Reviewed-by: NViktor Mihajlovski <mihajlov@linux.vnet.ibm.com>