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/arch/x86/Kconfig b/arch/x86/Kconfig
index bb3ff43..35d24e4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -76,6 +76,12 @@
 config DM_SERIAL
 	default y
 
+config SYS_MALLOC_F
+	default y
+
+config SYS_MALLOC_F_LEN
+	default 0x800
+
 config RAMBASE
 	hex
 	default 0x100000