Revert "cred: add missing return error code when set_cred_ucounts() failed"

Revert "cred: add missing return error code when set_cred_ucounts() failed"

This reverts commit 0855952ed4f1a6861fbb0e5d684efd447d7347c9 which is
commit 5e6b8a50a7cec5686ee2c4bda1d49899c79a7eae upstream.

The "original" commit 905ae01c4ae2 ("Add a reference to ucounts for each
cred"), should not have been applied to the 5.10.y tree, so revert it,
and the follow-on fixup patches as well.

Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/87v93k4bl6.fsf@disp2133
Cc: Yang Yingliang <yangyingliang@huawei.com>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>