[POWERPC] cell: use ppc_md->power_save instead of cbe_idle_loop

This moves the cell idle function to use the default cpu_idle
with a special power_save callback, like all other platforms
except iSeries already do.

It also makes it possible to disable this power_save function
with a new powerpc-specific boot option "powersave=off".

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/idle.c

@@ -39,6 +39,13 @@
 #define cpu_should_die()	0
 #endif
 
+static int __init powersave_off(char *arg)
+{
+	ppc_md.power_save = NULL;
+	return 0;
+}
+__setup("powersave=off", powersave_off);
+
 /*
  * The body of the idle task.
  */