5.10: fixing b58294ce1a8a ("um: Allow PM with suspend-to-idle")

[Johannes Berg <johannes@xxxxxxxxxxxxxxxx>]

Hi,

Not sure why this was backported in the first place, but if so you'd
also need 1fb1abc83636 ("um: Fix build w/o CONFIG_PM_SLEEP").

I think b58294ce1a8a ("um: Allow PM with suspend-to-idle") should just
be reverted, but picking up the fix for it also works.

Robot keeps reporting to me that it's broken :)

Thanks,
johannes