greybus: battery: move battery file to power_supply

Rename the battery.c to power_supply.c and update the makefile as the
Greybus protocol is being renamed from battery to power_supply.
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/Makefile

@@ -24,7 +24,7 @@ gb-phy-y :=	gpbridge.o	\
 
 # Prefix all modules with gb-
 gb-vibrator-y := vibrator.o
-gb-battery-y := battery.o
+gb-power-supply-y := power_supply.o
 gb-loopback-y := loopback.o
 gb-light-y := light.o
 gb-raw-y := raw.o
@@ -36,7 +36,7 @@ gb-db3-y := db3-platform.o
 obj-m += greybus.o
 obj-m += gb-phy.o
 obj-m += gb-vibrator.o
-obj-m += gb-battery.o
+obj-m += gb-power-supply.o
 obj-m += gb-loopback.o
 obj-m += gb-light.o
 obj-m += gb-hid.o