configs: icore: Fix U-Boot proper loading from nand

SPL on Engicam i.Core M6 boards enabled DM, so it would require some
malloc() pool before relocation in order to load U-Boot proper properly.

So, enable SPL malloc() pool of 0x2000 size similarly like what we have
used for icore mmc defconfigs.

Signed-off-by: Shyam Saini <shyam.saini@amarulasolutions.com>
diff --git a/configs/imx6qdl_icore_nand_defconfig b/configs/imx6qdl_icore_nand_defconfig
index 4ea0803..4672563 100644
--- a/configs/imx6qdl_icore_nand_defconfig
+++ b/configs/imx6qdl_icore_nand_defconfig
@@ -8,6 +8,7 @@
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_SPL=y
+CONFIG_SYS_MALLOC_F_LEN=0x2000
 # CONFIG_CMD_BMODE is not set
 CONFIG_FIT=y
 CONFIG_FIT_SIGNATURE=y