sandbox: use CONFIG_VAL(SYS_MALLOC_F_LEN) to distinguish malloc pool size before relocation

SPL and normal u-boot stage use different malloc pool size
configuration before relocation, so use CONFIG_VAL(SYS_MALLOC_F_LEN)
to fit different boot stage.

Signed-off-by: Andy Yan <andyshrk@gmail.com>

Changes in v3:
- use CONFIG_VAL(), which suggested by Simon

Changes in v2: None

 arch/sandbox/cpu/start.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index f605d4d..00742fd 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -310,7 +310,7 @@
 
 	memset(&data, '\0', sizeof(data));
 	gd = &data;
-#ifdef CONFIG_SYS_MALLOC_F_LEN
+#if CONFIG_VAL(SYS_MALLOC_F_LEN)
 	gd->malloc_base = CONFIG_MALLOC_F_ADDR;
 #endif
 	setup_ram_buf(state);