dm: core: Add SPL Kconfig for REGMAP and SYSCON

Add SPL Kconfig for REGMAP and SYSCON, so REGMAP and SYSCON can
remove from SPL stage.

Signed-off-by: Lin Huang <hl@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/Makefile b/drivers/core/Makefile
index f19f67d..07adb61 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -9,5 +9,5 @@
 obj-$(CONFIG_$(SPL_)DM_DEVICE_REMOVE)	+= device-remove.o
 obj-$(CONFIG_$(SPL_)SIMPLE_BUS)	+= simple-bus.o
 obj-$(CONFIG_DM)	+= dump.o
-obj-$(CONFIG_REGMAP)	+= regmap.o
-obj-$(CONFIG_SYSCON)	+= syscon-uclass.o
+obj-$(CONFIG_$(SPL_)REGMAP)	+= regmap.o
+obj-$(CONFIG_$(SPL_)SYSCON)	+= syscon-uclass.o