perf_cfg is enough - it already contains almost all necessary
information and is constructed in a more optimal way (O(n) vs O(n^2)
- it uses hash table to build the unique counter list).

"Almost all", because it doesn't contain OA raw counters, but
we should have not exposed them anyway. Quoting Mark Janes:
"I see no reason to include the OA raw counters in the list that
are provided to the user. They are unusable.
The MDAPI library can be used to configure raw counters in a way
that provides esoteric metrics, but that library is written against
INTEL_performance_query."

Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Mark Janes <mark.a.janes@intel.com>
Part-of: <!5399>