rockchip: add common tpl board file

Rockchip SoCs have similar boot process, prefer to use TPL for DRAM
init and back to bootrom, and SPL as Trust ATF/U-Boot loader. TPL
common board is a basic TPL board init which can be shared for most
of SoCs to avoid copy-pase for different SoCs.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/Makefile b/arch/arm/mach-rockchip/Makefile
index 9afbb05..2686e0c 100644
--- a/arch/arm/mach-rockchip/Makefile
+++ b/arch/arm/mach-rockchip/Makefile
@@ -8,6 +8,7 @@
 # the stack-pointer is valid before switching to the U-Boot stack).
 obj-spl-$(CONFIG_ROCKCHIP_BROM_HELPER) += bootrom.o
 obj-tpl-$(CONFIG_ROCKCHIP_BROM_HELPER) += bootrom.o
+obj-tpl-$(CONFIG_TPL_ROCKCHIP_COMMON_BOARD) += tpl.o
 
 obj-tpl-$(CONFIG_ROCKCHIP_RK3288) += rk3288-board-tpl.o
 obj-tpl-$(CONFIG_ROCKCHIP_RK3368) += rk3368-board-tpl.o