drm/i915/pmu: Use event_to_pmu()

i915 pointer is not needed in this function and all the others simply
calculate the i915_pmu container based on the event->pmu. Follow the
same logic as in other functions.

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240909204340.3646458-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Author: Lucas De Marchi

drivers/gpu/drm/i915/i915_pmu.c

@@ -834,15 +834,14 @@ static void i915_pmu_event_start(struct perf_event *event, int flags)
 
 static void i915_pmu_event_stop(struct perf_event *event, int flags)
 {
-	struct drm_i915_private *i915 =
-		container_of(event->pmu, typeof(*i915), pmu.base);
-	struct i915_pmu *pmu = &i915->pmu;
+	struct i915_pmu *pmu = event_to_pmu(event);
 
 	if (pmu->closed)
 		goto out;
 
 	if (flags & PERF_EF_UPDATE)
 		i915_pmu_event_read(event);
+
 	i915_pmu_disable(event);
 
 out: