dm: Kconfig: Move CONFIG_SYS_MALLOC_F_LEN to Kconfig

Move this option to Kconfig and update all boards.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/smdkc100_defconfig b/configs/smdkc100_defconfig
index 041030f..e933a32 100644
--- a/configs/smdkc100_defconfig
+++ b/configs/smdkc100_defconfig
@@ -2,3 +2,5 @@
 CONFIG_TARGET_SMDKC100=y
 CONFIG_ARCH_S5PC1XX=y
 CONFIG_DEFAULT_DEVICE_TREE="s5pc1xx-smdkc100"
+CONFIG_SYS_MALLOC_F=y
+CONFIG_SYS_MALLOC_F_LEN=0x400