spl: spi: Move CONFIG_SPL_SPI_LOAD to Kconfig

Add Kconfig entry for CONFIG_SPL_SPI_LOAD symbol and move all
configurations using it to Kconfig.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/configs/cl-som-am57x_defconfig b/configs/cl-som-am57x_defconfig
index 53746bf..873f80d 100644
--- a/configs/cl-som-am57x_defconfig
+++ b/configs/cl-som-am57x_defconfig
@@ -3,11 +3,13 @@
 CONFIG_OMAP54XX=y
 CONFIG_TARGET_CL_SOM_AM57X=y
 # CONFIG_SPL_NAND_SUPPORT is not set
+CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL=y
 CONFIG_DISTRO_DEFAULTS=y
 # CONFIG_USE_BOOTCOMMAND is not set
 CONFIG_VERSION_VARIABLE=y
 # CONFIG_SPL_EXT_SUPPORT is not set
+CONFIG_SPL_SPI_LOAD=y
 CONFIG_SYS_PROMPT="U-Boot# "
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_EEPROM=y