pseries: Clean up error handling of spapr_cpu_init()

pseries: Clean up error handling of spapr_cpu_init()

Currently spapr_cpu_init() is hardcoded to handle any errors as fatal.
That works for now, since it's only called from initial setup where an
error here means we really can't proceed.

However, we'll want to handle this more flexibly for cpu hotplug in future
so generalize this using the error reporting infrastructure.  While we're
at it make a small cleanup in a related part of ppc_spapr_init() to use
error_report() instead of an old-style explicit fprintf().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>