simplify get_cramfs_inode()

simply don't hash the inodes that don't have real inumber instead of
skipping them during iget5_locked(); as the result, simple iget_locked()
would do and we can get rid of cramfs ->drop_inode() as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/cramfs/inode.c
Simple merge