riscv: ax25: add SPL support

The U-Boot SPL will boot in M mode and load the FIT image which
include OpenSBI and U-Boot proper images. After loading progress,
it will jump to OpenSBI first and then U-Boot proper which will
run in S mode.

Also remove V5L2_CACHE due to U-Boot SPL code size consideration.
Without this concern, it can be enable manually for performance.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: KC Lin <kclin@andestech.com>
Cc: Alan Kao <alankao@andestech.com>

arch/riscv/cpu/ax25/Kconfig

@@ -6,7 +6,9 @@ config RISCV_NDS
 	imply RISCV_TIMER
 	imply ANDES_PLIC if (RISCV_MMODE || SPL_RISCV_MMODE)
 	imply ANDES_PLMT if (RISCV_MMODE || SPL_RISCV_MMODE)
-	imply V5L2_CACHE
+	imply SPL_CPU_SUPPORT
+	imply SPL_OPENSBI
+	imply SPL_LOAD_FIT
 	help
 	  Run U-Boot on AndeStar V5 platforms and use some specific features
 	  which are provided by Andes Technology AndeStar V5 families.