riscv: sifive: fu540: add SPL configuration

Add a support for SPL which will boot from L2 LIM (0x0800_0000) and
then SPL will boot U-Boot FIT image (OpenSBI FW_DYNAMIC + u-boot.bin)
from MMC boot devices.

SPL related code is leveraged from FSBL
(https://github.com/sifive/freedom-u540-c000-bootloader.git)

Signed-off-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/board/sifive/fu540/Kconfig b/board/sifive/fu540/Kconfig
index eb5ba31..4a77a2a 100644
--- a/board/sifive/fu540/Kconfig
+++ b/board/sifive/fu540/Kconfig
@@ -13,12 +13,20 @@
 	default "sifive-fu540"
 
 config SYS_TEXT_BASE
+	default 0x80200000 if SPL
 	default 0x80000000 if !RISCV_SMODE
 	default 0x80200000 if RISCV_SMODE
 
+config SPL_TEXT_BASE
+	default 0x08000000
+
+config SPL_OPENSBI_LOAD_ADDR
+	default 0x80000000
+
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y
-	select GENERIC_RISCV
+	select SIFIVE_FU540
+	select SUPPORT_SPL
 	select RAM
 	select SPL_RAM if SPL
 	imply CMD_DHCP