Linux 5.5 rc4

To absolutely nobody's surprise, last week was very quiet indeed. It's
hardly even worth making an rc release, but there are _some_ fixes in
here, so here's the usual weekly Sunday afternoon rc.

It's drivers (gpio, i915, scsi, libata), some cifs fixes, and io_uring
fixes. And some kunit/selftest updates. And one or two other random
small things.

Go test it, you still have some time before the New Year's Eve
celebrations commence. Let's all hope for a happy new year, but I
suspect the next rc is going to be on the small side too as most
people are probably still in holiday mode..