[POWERPC] ps3: remove cpuinfo

Remove the unneded routine ps3_show_cpuinfo().  The common platform code now
prints the same information.

Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>