Kernel prepatch 6.9-rc3

The 6.9-rc3 kernel prepatch is out for
testing.

Ok, so this rc3 looks a bit different than the usual ones, because
there's a large series to bcachefs to do filesystem repair after
corruption. Not normally something we'd see in an rc kernel, but
hey, if you had a corrupted bcachefs filesystem you'd probably want
this, and if you thought bcachefs was stable already, I have a
bridge to sell you. Special deal only for you, real cheap.