rockchip: add config decide whether to build common.c

some rockchips soc will not use uclass in SPL stage,
so define config to decide whether to build common.c

Signed-off-by: Lin Huang <hl@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

arch/arm/mach-rockchip/Makefile

@@ -9,6 +9,6 @@ obj-$(CONFIG_ROCKCHIP_RK3288) += rk3288-board-spl.o
 else
 obj-y += board.o
 endif
-obj-y += common.o
 obj-y += rk_timer.o
+obj-$(CONFIG_$(SPL_)ROCKCHIP_COMMON) += common.o
 obj-$(CONFIG_ROCKCHIP_RK3288) += rk3288/

include/configs/rk3288_common.h

@@ -42,6 +42,9 @@
 #define CONFIG_SPL_STACK		0xff718000
 #define CONFIG_SPL_TEXT_BASE		0xff704004
 
+#define CONFIG_ROCKCHIP_COMMON
+#define CONFIG_SPL_ROCKCHIP_COMMON
+
 /* MMC/SD IP block */
 #define CONFIG_MMC
 #define CONFIG_GENERIC_MMC