FS/OMFS: block number sanity check during fill_super operation

FS/OMFS: block number sanity check during fill_super operation

This patch defines maximum block number to 2^31.  It also converts
bitmap_size and array_size to unsigned int in omfs_get_imap

Signed-off-by: Fabian Frederick <[email protected]>
Suggested-by: Linus Torvalds <[email protected]>
Suggested-by: Bob Copeland <[email protected]>
Acked-by: Bob Copeland <[email protected]>
Tested-by: Bob Copeland <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>