cpuidle-haltpoll: return -ENODEV on modinit failure

mainline inclusion
from mainline-5.4
commit 5cc59f59
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=34


CVE: NA

When a user loads cpuidle-haltpoll on a non KVM guest the module will
successfully load, even though idle driver registration didn't take
place.

We should instead return -ENODEV signaling the user that the driver can't
be loaded, like other error paths in haltpoll_init().  An example of such
error paths is when we return -EBUSY when attempting to register an idle
driver when it had one already (e.g. intel_idle loads at boot and then we
attempt to insert module cpuidle-haltpoll).

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Signed-off-by: Xiangyou Xie <xiexiangyou@huawei.com>
Reviewed-by: Hailiang Zhang <zhang.zhanghailiang@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jiajun Chen <chenjiajun8@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>