at91, smartweb: use SPL_SYS_MALLOC_F_LEN

commit f1896c45cb2f: spl: make SPL and normal u-boot stage use independent SYS_MALLOC_F_LEN
introduced independent SYS_MALLOC_F_LEN for SPL and U-Boot.

Use it on the smartweb board, as above commit broke
the smartweb board.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/configs/smartweb_defconfig b/configs/smartweb_defconfig
index 1db2acc..92359f4 100644
--- a/configs/smartweb_defconfig
+++ b/configs/smartweb_defconfig
@@ -10,6 +10,7 @@
 CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_DEFAULT_DEVICE_TREE="at91sam9260-smartweb"
+CONFIG_SPL_SYS_MALLOC_F_LEN=0x400
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9260"
 CONFIG_ENV_IS_IN_NAND=y