jfs: remove unnecessary nlink setting

alloc_inode() initializes i_nlink to 1.  Remove unnecessary
re-initialization.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>