more trivial ->iterate_shared conversions

fs/bfs/dir.c

fs/cramfs/inode.c

fs/efs/dir.c

fs/exofs/dir.c

fs/freevxfs/vxfs_lookup.c

fs/jffs2/dir.c

fs/libfs.c

fs/logfs/dir.c

fs/nilfs2/dir.c

fs/omfs/dir.c

fs/openpromfs/inode.c

fs/qnx4/dir.c

fs/qnx6/dir.c

fs/reiserfs/dir.c

fs/ubifs/dir.c

fs/udf/dir.c