[POWERPC] atomic.h: Add atomic64 cmpxchg, xchg and add_unless to powerpc

atomic.h : Add atomic64 cmpxchg, xchg and add_unless to powerpc

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>
1 file changed