Convert CONFIG_SPL_SPI_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/T1023RDB_SPIFLASH_defconfig b/configs/T1023RDB_SPIFLASH_defconfig
index 907a5dc..1920471 100644
--- a/configs/T1023RDB_SPIFLASH_defconfig
+++ b/configs/T1023RDB_SPIFLASH_defconfig
@@ -5,6 +5,7 @@
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
+CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_MPC85xx=y
 CONFIG_TARGET_T102XRDB=y
 CONFIG_FIT=y