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/zynq_zc770_xm010_defconfig b/configs/zynq_zc770_xm010_defconfig
index 683dfe8..fe23dc1 100644
--- a/configs/zynq_zc770_xm010_defconfig
+++ b/configs/zynq_zc770_xm010_defconfig
@@ -14,6 +14,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_OS_BOOT=y
+CONFIG_SPL_SPI_LOAD=y
 CONFIG_SYS_PROMPT="Zynq> "
 # CONFIG_CMD_FLASH is not set
 CONFIG_CMD_FPGA_LOADBP=y