Revert "btrfs: add ASSERTs on prealloc in qgroup functions"

Revert "btrfs: add ASSERTs on prealloc in qgroup functions"

This reverts commit 252877a8701530fde861a4f27710c1e718e97caa.

Commit 252877a87015 ("btrfs: add ASSERTs on prealloc in qgroup
functions") tries to remove the kfree() on preallocated qgroup during
several call sites, but this cannot work as intended:

- btrfs_quota_enable()
- btrfs_create_qgroup()
  If add_qgroup_item() failed, we go out_free_path() and at that time
  prealloc is not yet utilized and will trigger the new ASSERT().

- btrfs_qgroup_inherit()
  If qgroup_auto_inherit() failed, prealloc is not yet utilized and
  will trigger the new ASSERT()

Reported-by: syzbot+b44d4a4885bc82af2a06@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/69369331.a70a0220.38f243.009e.GAE@google.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>