sysfs: consolidate sysfs spinlocks

Replace sysfs_lock and kobj_sysfs_assoc_lock with sysfs_assoc_lock.
sysfs_lock was originally to be used to protect sysfs_dirent tree but
mutex seems better choice, so there is no reason to keep sysfs_lock
separate.  Merge the two spinlocks into one.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 27a5f4b..4572677 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -81,8 +81,7 @@
 extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
 extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
 
-extern spinlock_t sysfs_lock;
-extern spinlock_t kobj_sysfs_assoc_lock;
+extern spinlock_t sysfs_assoc_lock;
 extern struct rw_semaphore sysfs_rename_sem;
 extern struct super_block * sysfs_sb;
 extern const struct file_operations sysfs_dir_operations;