riscv: ae350: Fix OF_BOARD boot failure

Enable OF_HAS_PRIOR_STAGE for ae350 boards with OF_BOARD

Fixes: 239d22c7 ("fdt: Enable OF_HAS_PRIOR_STAGE for most boards with OF_BOARD")
Signed-off-by: NRick Chen <rick@andestech.com>
Reviewed-by: NLeo Yu-Chi Liang <ycliang@andestech.com>

board/AndesTech/ax25-ae350/Kconfig

@@ -35,5 +35,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	imply SMP
 	imply SPL_RAM_SUPPORT
 	imply SPL_RAM_DEVICE
+	imply OF_HAS_PRIOR_STAGE
 
 endif