powerpc/qspinlock: Propagate sleepy if previous waiter is preempted

The sleepy (aka lock-owner-is-preempted) condition is propagated down
the queue by each waiter. If a waiter becomes preempted, it can no
longer propagate sleepy. To allow subsequent waiters to yield to the
lock owner, also check the lock owner in this case.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Reviewed-by: "Nysal Jan K.A" <nysal@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231016124305.139923-6-npiggin@gmail.com