sifive: fu540: Enable SF distro bootcmd

Enable SPI flash(SF) distro boot command in Sifive FU540.

This distro boot will read the boot script at specific
location at the flash and start sourcing the same.

Included the SF device at the last of the target devices
list since all the rest of the devices on the list have
more possibility to boot the distribution due to the
size of the SPI flash is concern.
Signed-off-by: NJagan Teki <jagan@amarulasolutions.com>
Reviewed-by: NBin Meng <bin.meng@windriver.com>

include/configs/sifive-fu540.h

@@ -43,9 +43,11 @@
 #ifndef CONFIG_SPL_BUILD
 #define BOOT_TARGET_DEVICES(func) \
 	func(MMC, mmc, 0) \
+	func(SF, sf, 0) \
 	func(DHCP, dhcp, na)
 
 #include <config_distro_bootcmd.h>
+#include <environment/distro/sf.h>
 
 #define TYPE_GUID_LOADER1	"5B193300-FC78-40CD-8002-E86C45580B47"
 #define TYPE_GUID_LOADER2	"2E54B353-1271-4842-806F-E436D6AF6985"
@@ -70,7 +72,8 @@
 	"type_guid_gpt_loader2=" TYPE_GUID_LOADER2 "\0" \
 	"type_guid_gpt_system=" TYPE_GUID_SYSTEM "\0" \
 	"partitions=" PARTS_DEFAULT "\0" \
-	BOOTENV
+	BOOTENV \
+	BOOTENV_SF
 
 #define CONFIG_PREBOOT \
 	"setenv fdt_addr ${fdtcontroladdr};" \