drm/i915/pmu: Check actual RC6 status

RC6 support cannot be simply established by looking at the static device
HAS_RC6() flag. There are cases which disable RC6 at driver load time so
use the status of those check when deciding whether to enumerate the rc6
counter.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reported-by: Eero T Tamminen <eero.t.tamminen@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210331101850.2582027-1-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/i915_pmu.c

@@ -476,6 +476,8 @@ engine_event_status(struct intel_engine_cs *engine,
 static int
 config_status(struct drm_i915_private *i915, u64 config)
 {
+	struct intel_gt *gt = &i915->gt;
+
 	switch (config) {
 	case I915_PMU_ACTUAL_FREQUENCY:
 		if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
@@ -489,7 +491,7 @@ config_status(struct drm_i915_private *i915, u64 config)
 	case I915_PMU_INTERRUPTS:
 		break;
 	case I915_PMU_RC6_RESIDENCY:
-		if (!HAS_RC6(i915))
+		if (!gt->rc6.supported)
 			return -ENODEV;
 		break;
 	case I915_PMU_SOFTWARE_GT_AWAKE_TIME: