spi: Rename SPI_SUPPORT to SPI

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/thuban_defconfig b/configs/thuban_defconfig
index 5dc6587..5daa63a 100644
--- a/configs/thuban_defconfig
+++ b/configs/thuban_defconfig
@@ -21,7 +21,7 @@
 CONFIG_SPL_FS_FAT=y
 CONFIG_SPL_LIBDISK_SUPPORT=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
-CONFIG_SPL_SPI_SUPPORT=y
+CONFIG_SPL_SPI=y
 CONFIG_ENV_VARS_UBOOT_CONFIG=y
 CONFIG_SYS_LOAD_ADDR=0x81000000
 CONFIG_BOOTDELAY=3