Don't compile the PMU power driver on 64-bit PowerPC

As reported by Stephen Rothwell, an allmodconfig build on 64-bit
PowerPC reports these errors:

ERROR: "pmu_batteries" [drivers/power/pmu_battery.ko] undefined!
ERROR: "pmu_battery_count" [drivers/power/pmu_battery.ko] undefined!
ERROR: "pmu_power_flags" [drivers/power/pmu_battery.ko] undefined!

This fixes the problem by not building pmu_battery.ko on ppc64.  There
are no battery-powered ppc64 machines with an Apple PMU, and we can be
reasonably confident there never will be.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/power/Kconfig

@@ -38,7 +38,7 @@ config BATTERY_DS2760
 
 config BATTERY_PMU
 	tristate "Apple PMU battery"
-	depends on ADB_PMU
+	depends on PPC32 && ADB_PMU
 	help
 	  Say Y here to expose battery information on Apple machines
 	  through the generic battery class.