platform/cpufreq: add public defines for CPUFREQ_SHARED_TYPE_

platform/cpufreq: add public defines for CPUFREQ_SHARED_TYPE_

The values set in the shared_type field of xen_processor_performance
have so far relied on Xen and Linux having the same
CPUFREQ_SHARED_TYPE_ defines, as those have never been part of the
public interface.

Formalize by adding the defines for the allowed values in the public
header, while renaming them to use the XEN_CPUPERF_SHARED_TYPE_ prefix
for clarity.

Set the Xen internal defines for CPUFREQ_SHARED_TYPE_ using the newly
introduced XEN_CPUPERF_SHARED_TYPE_ public defines in order to avoid
unnecessary code churn.  While there also drop
CPUFREQ_SHARED_TYPE_NONE as it's unused.

Fixes: 2fa7bee0a0 ('Get ACPI Px from dom0 and choose Px controller')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>