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/common/spl/Kconfig b/common/spl/Kconfig
index d15f576..9697173 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -643,6 +643,13 @@
 	  lines). This enables the drivers in drivers/mtd/spi as part of an
 	  SPL build. This normally requires SPL_SPI_SUPPORT.
 
+config SPL_SPI_LOAD
+	bool "Support loading from SPI flash"
+	depends on SPL_SPI_FLASH_SUPPORT
+	help
+	  Enable support for loading next stage, U-Boot or otherwise, from
+	  SPI NOR in U-Boot SPL.
+
 config SPL_SPI_SUPPORT
 	bool "Support SPI drivers"
 	help