remove "struct subsystem" as it is no longer needed

We need to work on cleaning up the relationship between kobjects, ksets and
ktypes.  The removal of 'struct subsystem' is the first step of this,
especially as it is not really needed at all.

Thanks to Kay for fixing the bugs in this patch.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 095a9c9..7c0077f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1416,7 +1416,7 @@
 extern int vfs_statfs(struct dentry *, struct kstatfs *);
 
 /* /sys/fs */
-extern struct subsystem fs_subsys;
+extern struct kset fs_subsys;
 
 #define FLOCK_VERIFY_READ  1
 #define FLOCK_VERIFY_WRITE 2