intel/perf: document meaning of query field

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Mark Janes <mark.a.janes@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4344>

src/intel/perf/gen_perf.h

@@ -189,6 +189,7 @@ struct gen_perf_query_info {
 };
 
 struct gen_perf_config {
+   /* Whether i915 has DRM_I915_QUERY_PERF_CONFIG support. */
    bool i915_query_supported;
 
    struct gen_perf_query_info *queries;