Generalise the handling of MTD-specific superblocks so that JFFS2 and ROMFS
can both share it.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>