[POWERPC] PS3: Sys-manager Wake-on-LAN support

Add Wake-on-LAN support to the PS3 system-manager.  Other OS WOL
support was introduced in PS3 system firmware 2.20.

Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>