powerpc: perf_event: Log invalid data addresses as all 1s

When we take an exception and the SDAR isn't synchronised we currently
log 0 as the address.  Unfortunately this is a pretty common value, so
use ~0UL instead.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>