sunxi: add DRAM_SUN6I kconfig

Add proper and simple kconfig option for dram_sun6i.c
instead of using MACH type on Makefile.
Signed-off-by: NJagan Teki <jagan@amarulasolutions.com>
Acked-by: NMaxime Ripard <maxime.ripard@bootlin.com>

arch/arm/mach-sunxi/Kconfig

@@ -6,6 +6,12 @@ config SPL_LDSCRIPT
 config IDENT_STRING
 	default " Allwinner Technology"
 
+config DRAM_SUN6I
+	bool
+	help
+	  Select this dram controller driver for Sun6i platforms,
+	  like A31/A31s.
+
 config SUN6I_P2WI
 	bool "Allwinner sun6i internal P2WI controller"
 	help
@@ -119,6 +125,7 @@ config MACH_SUN6I
 	select CPU_V7_HAS_NONSEC
 	select CPU_V7_HAS_VIRT
 	select ARCH_SUPPORT_PSCI
+	select DRAM_SUN6I
 	select SUN6I_P2WI
 	select SUN6I_PRCM
 	select SUNXI_GEN_SUN6I

arch/arm/mach-sunxi/Makefile

@@ -33,9 +33,9 @@ endif
 obj-$(CONFIG_MACH_SUN9I)	+= clock_sun9i.o gtbus_sun9i.o
 
 ifdef CONFIG_SPL_BUILD
+obj-$(CONFIG_DRAM_SUN6I)	+= dram_sun6i.o
 obj-$(CONFIG_MACH_SUN4I)	+= dram_sun4i.o
 obj-$(CONFIG_MACH_SUN5I)	+= dram_sun4i.o
-obj-$(CONFIG_MACH_SUN6I)	+= dram_sun6i.o
 obj-$(CONFIG_MACH_SUN7I)	+= dram_sun4i.o
 obj-$(CONFIG_MACH_SUN8I_A23)	+= dram_sun8i_a23.o
 obj-$(CONFIG_MACH_SUN8I_A33)	+= dram_sun8i_a33.o