Convert CONFIG_SPL_POWER_SUPPORT to Kconfig

Move this option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/brppt1_nand_defconfig b/configs/brppt1_nand_defconfig
index a3d7638..1c01bd4 100644
--- a/configs/brppt1_nand_defconfig
+++ b/configs/brppt1_nand_defconfig
@@ -4,12 +4,13 @@
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_SPL_I2C_SUPPORT=y
+CONFIG_SPL_NAND_SUPPORT=y
+CONFIG_SPL_POWER_SUPPORT=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_SYS_EXTRA_OPTIONS="SERIAL1,CONS_INDEX=1,NAND"
 CONFIG_BOOTDELAY=-2
 CONFIG_VERSION_VARIABLE=y
 CONFIG_SPL=y
-CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMI is not set