bcachefs: mark invalid_btree_id autofix

Checking for invalid IDs was introduced in 9e7cfb35 ("bcachefs: Check for invalid btree IDs")
to prevent an invalid shift later, but since 14152654 ("bcachefs: Bad btree roots are now autofix")
which made btree_root_bkey_invalid autofix, the fsck_err_on call didn't
do anything.

We can mark this err type (invalid_btree_id) autofix as well, so it gets
handled.

Reported-by:  <syzbot+029d1989099aa5ae3e89@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=029d1989099aa5ae3e89


Fixes: 14152654 ("bcachefs: Bad btree roots are now autofix")

Signed-off-by: Bharadwaj Raju <bharadwaj.raju777@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>