davinci: omapl138-lcdk: enable SPL_SYS_MALLOC_SIMPLE

We're working towards enabling the driver model in SPL for da850-lcdk.
Enable SPL_SYS_MALLOC_SIMPLE in defconfig to reduce SPL size.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
diff --git a/configs/omapl138_lcdk_defconfig b/configs/omapl138_lcdk_defconfig
index fa4ce69..bfb88e3 100644
--- a/configs/omapl138_lcdk_defconfig
+++ b/configs/omapl138_lcdk_defconfig
@@ -18,6 +18,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_TEXT_BASE=0x80000000
+CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0xb5
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_HUSH_PARSER=y