perf/arm_cspmu: Fix event attribute type

ARM_CSPMU_EVENT_ATTR() defines a struct perf_pmu_events_attr, so
arm_cspmu_sysfs_event_show() should not be interpreting it as struct
dev_ext_attribute.

Fixes: e37dfd65 ("perf: arm_cspmu: Add support for ARM CoreSight PMU driver")
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-and-tested-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/27c0804af64007b2400abbc40278f642ee6a0a29.1685983270.git.robin.murphy@arm.comSigned-off-by: Will Deacon <will@kernel.org>

drivers/perf/arm_cspmu/arm_cspmu.c

@@ -189,10 +189,10 @@ static inline bool use_64b_counter_reg(const struct arm_cspmu *cspmu)
 ssize_t arm_cspmu_sysfs_event_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
-	struct dev_ext_attribute *eattr =
-		container_of(attr, struct dev_ext_attribute, attr);
-	return sysfs_emit(buf, "event=0x%llx\n",
-			  (unsigned long long)eattr->var);
+	struct perf_pmu_events_attr *pmu_attr;
+
+	pmu_attr = container_of(attr, typeof(*pmu_attr), attr);
+	return sysfs_emit(buf, "event=0x%llx\n", pmu_attr->id);
 }
 EXPORT_SYMBOL_GPL(arm_cspmu_sysfs_event_show);