coresight: Fix DEBUG_LOCKS_WARN_ON for uninitialized attribute

While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled,
I get the following splat.

 BUG: key ffffcb5636929298 has not been registered!
 ------------[ cut here ]------------
 DEBUG_LOCKS_WARN_ON(1)
 WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0
 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G        W         5.2.0-next-20190712-00015-g00ad4634222e-dirty #603
 Workqueue: events amba_deferred_retry_func
 pstate: 60c00005 (nZCv daif +PAN +UAO)
 pc : lockdep_init_map+0x164/0x1f0
 lr : lockdep_init_map+0x164/0x1f0

 [ trimmed ]

 Call trace:
  lockdep_init_map+0x164/0x1f0
  __kernfs_create_file+0x9c/0x158
  sysfs_add_file_mode_ns+0xa8/0x1d0
  sysfs_add_file_to_group+0x88/0xd8
  etm_perf_add_symlink_sink+0xcc/0x138
  coresight_register+0x110/0x280
  tmc_probe+0x160/0x420

 [ trimmed ]

 ---[ end trace ab4cc669615ba1b0 ]---

Fix this by initialising the dynamically allocated attribute properly.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Fixes: bb8e370b ("coresight: perf: Add "sinks" group to PMU directory")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
[Fixed a typograhic error in the changelog]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20190801172323.18359-2-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-etm-perf.c

@@ -544,6 +544,7 @@ int etm_perf_add_symlink_sink(struct coresight_device *csdev)
 	/* See function coresight_get_sink_by_id() to know where this is used */
 	hash = hashlen_hash(hashlen_string(NULL, name));
 
+	sysfs_attr_init(&ea->attr.attr);
 	ea->attr.attr.name = devm_kstrdup(dev, name, GFP_KERNEL);
 	if (!ea->attr.attr.name)
 		return -ENOMEM;