powerpc: Unify the 32 and 64 bit idle loops

This unifies the 32-bit (ARCH=ppc and ARCH=powerpc) and 64-bit idle
loops.  It brings over the concept of having a ppc_md.power_save
function from 32-bit to ARCH=powerpc, which lets us get rid of
native_idle().  With this we will also be able to simplify the idle
handling for pSeries and cell.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 676f894..e39f830 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -53,9 +53,6 @@
 extern void platform_init(void);
 extern void bootx_init(unsigned long r4, unsigned long phys);
 
-extern void ppc6xx_idle(void);
-extern void power4_idle(void);
-
 boot_infos_t *boot_infos;
 struct ide_machdep_calls ppc_ide_md;
 
@@ -194,7 +191,9 @@
 	platform_init();
 
 #ifdef CONFIG_6xx
-	ppc_md.power_save = ppc6xx_idle;
+	if (cpu_has_feature(CPU_FTR_CAN_DOZE) ||
+	    cpu_has_feature(CPU_FTR_CAN_NAP))
+		ppc_md.power_save = ppc6xx_idle;
 #endif
 
 	if (ppc_md.progress)