bcachefs: Add missing wakeup to bch2_inode_hash_remove()

This fixes two different bugs:

- Looser locking with the rhashtable means we need to recheck if the
  inode is still hashed after prepare_to_wait(), and add a corresponding
  wakeup after removing from the hash table.

- da18ecbf ("fs: add i_state helpers") changed the bit waitqueues
  used for inodes, and bcachefs wasn't updated and thus broke; this
  updates bcachefs to the new helper.

Fixes: 112d21fd ("bcachefs: switch to rhashtable for vfs inodes hash")
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>