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/dra7xx_hs_evm_defconfig b/configs/dra7xx_hs_evm_defconfig
index d2e72c6..2ddd8eb 100644
--- a/configs/dra7xx_hs_evm_defconfig
+++ b/configs/dra7xx_hs_evm_defconfig
@@ -4,6 +4,7 @@
 CONFIG_TI_SECURE_DEVICE=y
 CONFIG_TARGET_DRA7XX_EVM=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
+CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_SPL_STACK_R_ADDR=0x82000000
 CONFIG_DEFAULT_DEVICE_TREE="dra7-evm"
 CONFIG_FIT=y