The P9 path always uses one vcpu per vcore, so none of the vcore, locks,
stolen time, blocking logic, shared waitq, etc., is required.

Remove most of it.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-51-npiggin@gmail.com