[PATCH] md: use queue_hardsect_size instead of block_size for md superblock size calc.

Doh.  I want the physical hard-sector-size, not the current block size...

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>