sunxi: Add DRAM_SUN9I kconfig entry

Add proper and simple kconfig option for dram_sun9i.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 054d925..93e5406 100644
--- a/arch/arm/mach-sunxi/Makefile
+++ b/arch/arm/mach-sunxi/Makefile
@@ -35,11 +35,11 @@
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_DRAM_SUN4I)	+= dram_sun4i.o
 obj-$(CONFIG_DRAM_SUN6I)	+= dram_sun6i.o
+obj-$(CONFIG_DRAM_SUN9I)	+= dram_sun9i.o
 obj-$(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
 obj-$(CONFIG_SPL_SPI_SUNXI)	+= spl_spi_sunxi.o
 obj-$(CONFIG_SUNXI_DRAM_DW)	+= dram_sunxi_dw.o
 obj-$(CONFIG_SUNXI_DRAM_DW)	+= dram_timings/
-obj-$(CONFIG_MACH_SUN9I)	+= dram_sun9i.o
 endif