power: Add CONFIG_SPL_POWER_DOMAIN config

Add CONFIG_SPL_POWER_DOMAIN config entry.
Build drivers/power/domain if this config is selected.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/Makefile b/drivers/Makefile
index 276e5ee..d532085 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -28,6 +28,7 @@
 obj-$(CONFIG_ALTERA_SDRAM) += ddr/altera/
 obj-$(CONFIG_SPL_POWER_SUPPORT) += power/ power/pmic/
 obj-$(CONFIG_SPL_POWER_SUPPORT) += power/regulator/
+obj-$(CONFIG_SPL_POWER_DOMAIN) += power/domain/
 obj-$(CONFIG_SPL_DM_RESET) += reset/
 obj-$(CONFIG_SPL_MTD_SUPPORT) += mtd/
 obj-$(CONFIG_SPL_ONENAND_SUPPORT) += mtd/onenand/