ext4: move sysfs code from super.c to fs/ext4/sysfs.c

Also statically allocate the ext4_kset and ext4_feat objects, since we
only need exactly one of each, and it's simpler and less code if we
drop the dynamic allocation and deallocation when it's not needed.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/Makefile

@@ -8,7 +8,7 @@ ext4-y	:= balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
 		ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
 		ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o \
 		mmp.o indirect.o extents_status.o xattr.o xattr_user.o \
-		xattr_trusted.o inline.o readpage.o
+		xattr_trusted.o inline.o readpage.o sysfs.o
 
 ext4-$(CONFIG_EXT4_FS_POSIX_ACL)	+= acl.o
 ext4-$(CONFIG_EXT4_FS_SECURITY)		+= xattr_security.o