Add PS3 logical performance monitor (lpm) device driver.

The PS3's LV1 hypervisor provides a Logical Performance Monitor that
abstracts the Cell processor's performance monitor features for use
by guest operating systems.
Signed-off-by: Takashi Yamamoto <TakashiA.Yamamoto@jp.sony.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>