bcachefs: bch2_str_hash_check_key() now checks inode hash info

bcachefs: bch2_str_hash_check_key() now checks inode hash info

Versions of the same inode in different snapshots must have the same
hash info; this is critical for lookups to work correctly.

We're going to be running the str_hash checks online, at readdir or
xattr list time, so we now need str_hash_check_key() to check for inode
hash seed mismatches, since it won't be run right after check_inodes().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>