btrfs: move sysfs declarations out of ctree.h

As the header for sysfs code already exists, use it to clean up ctree.h.

Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/super.c

@@ -43,6 +43,7 @@
 #include "free-space-cache.h"
 #include "backref.h"
 #include "space-info.h"
+#include "sysfs.h"
 #include "tests/btrfs-tests.h"
 #include "block-group.h"