drm/i915/pmu: fix noderef.cocci warnings

drivers/gpu/drm/i915/i915_pmu.c:795:34-40: ERROR: application of sizeof to pointer

 sizeof when applied to a pointer typed expression gives the size of
 the pointer

Generated by: scripts/coccinelle/misc/noderef.cocci

Fixes: 109ec558370f ("drm/i915/pmu: Only enumerate available counters in sysfs")
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180112170340.5387-1-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/i915_pmu.c

@@ -794,7 +794,7 @@ create_event_attributes(struct drm_i915_private *i915)
 		goto err_alloc;
 
 	/* Max one pointer of each attribute type plus a termination entry. */
-	attr = kzalloc((count * 2 + 1) * sizeof(attr), GFP_KERNEL);
+	attr = kzalloc((count * 2 + 1) * sizeof(*attr), GFP_KERNEL);
 	if (!attr)
 		goto err_alloc;