riscv: spl: add FIT name for RISC-V Falcon mode

The FIT name in RISC-V Falcon mode should be different from that in
normal boot mode; it is called linux.itb. If the setting is missing
in common/spl, the normal boot file name will be used.

Signed-off-by: Randolph <randolph@andestech.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 240543c..4e56d99 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -751,6 +751,7 @@
 	depends on SPL_FS_EXT4 || SPL_FS_FAT || SPL_FS_SQUASHFS || SPL_SEMIHOSTING
 	default "tispl.bin" if SYS_K3_SPL_ATF
 	default "u-boot.itb" if SPL_LOAD_FIT
+	default "linux.itb" if SPL_LOAD_FIT_OPENSBI_OS_BOOT
 	default "u-boot.img"
 	help
 	  Filename to read to load U-Boot when reading from filesystem.