x86/events/amd/iommu: Fix sizeof mismatch

An incorrect sizeof is being used, struct attribute ** is not correct,
it should be struct attribute *. Note that since ** is the same size as
* this is not causing any issues.  Improve this fix by using sizeof(*attrs)
as this allows us to not even reference the type of the pointer.

Addresses-Coverity: ("Sizeof not portable (SIZEOF_MISMATCH)")
Fixes: 51686546 ("x86/events/amd/iommu: Fix sysfs perf attribute groups")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201001113900.58889-1-colin.king@canonical.com

arch/x86/events/amd/iommu.c

@@ -379,7 +379,7 @@ static __init int _init_events_attrs(void)
 	while (amd_iommu_v2_event_descs[i].attr.attr.name)
 		i++;
 
-	attrs = kcalloc(i + 1, sizeof(struct attribute **), GFP_KERNEL);
+	attrs = kcalloc(i + 1, sizeof(*attrs), GFP_KERNEL);
 	if (!attrs)
 		return -ENOMEM;