Change 2d1b202762 ("powerpc: Fixup
lwsync at runtime") removed __SUBARCH_HAS_LWSYNC, causing smp_wmb to
revert back to eieio for all CPUs. This restores the behaviour
intorduced in 74f0609526 ("powerpc:
Optimise smp_wmb on 64-bit processors").
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
46d075be58