sunxi: Add DRAM_SUN4I kconfig entry

Add proper and simple kconfig option for dram_sun4i.c
instead of using MACH type on Makefile.

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 2d416e7..054d925 100644
--- a/arch/arm/mach-sunxi/Makefile
+++ b/arch/arm/mach-sunxi/Makefile
@@ -33,10 +33,8 @@
 obj-$(CONFIG_MACH_SUN9I)	+= clock_sun9i.o gtbus_sun9i.o
 
 ifdef CONFIG_SPL_BUILD
+obj-$(CONFIG_DRAM_SUN4I)	+= dram_sun4i.o
 obj-$(CONFIG_DRAM_SUN6I)	+= dram_sun6i.o
-obj-$(CONFIG_MACH_SUN4I)	+= dram_sun4i.o
-obj-$(CONFIG_MACH_SUN5I)	+= dram_sun4i.o
-obj-$(CONFIG_MACH_SUN7I)	+= dram_sun4i.o
 obj-$(CONFIG_MACH_SUN8I_A23)	+= dram_sun8i_a23.o
 obj-$(CONFIG_MACH_SUN8I_A33)	+= dram_sun8i_a33.o
 obj-$(CONFIG_MACH_SUN8I_A83T)	+= dram_sun8i_a83t.o