sunxi: Add SUN6I_PRCM kconfig entry

Add simple and meaningful kconfig option for prcm.c
instead of using MACH type on Makefile.

PRCM (Power/Reset/Clock Management) is considered as a
Multi-Functional Device, so used the same on Kconfig definition.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
diff --git a/arch/arm/mach-sunxi/Makefile b/arch/arm/mach-sunxi/Makefile
index 6ddf682..9713fd5 100644
--- a/arch/arm/mach-sunxi/Makefile
+++ b/arch/arm/mach-sunxi/Makefile
@@ -16,7 +16,7 @@
 ifndef CONFIG_MACH_SUN9I
 obj-y	+= usb_phy.o
 endif
-obj-$(CONFIG_MACH_SUN6I)	+= prcm.o
+obj-$(CONFIG_SUN6I_PRCM)	+= prcm.o
 obj-$(CONFIG_MACH_SUN8I)	+= prcm.o
 obj-$(CONFIG_MACH_SUN9I)	+= prcm.o
 obj-$(CONFIG_MACH_SUN6I)	+= p2wi.o