rockchip: rk3288: Migrate to use common board file

Use common board file for board_init() and board_late_init(),
for Rockchip SoCs have very similar process.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/Kconfig b/arch/arm/mach-rockchip/Kconfig
index 86b01df..b75c209 100644
--- a/arch/arm/mach-rockchip/Kconfig
+++ b/arch/arm/mach-rockchip/Kconfig
@@ -80,6 +80,7 @@
 	select SUPPORT_SPL
 	select SPL
 	select SUPPORT_TPL
+	imply ROCKCHIP_COMMON_BOARD
 	imply SPL_ROCKCHIP_COMMON_BOARD
 	imply TPL_CLK
 	imply TPL_DM