spl: Enable CONFIG_SPL_SYS_MALLOC_F where needed

Enable CONFIG_SPL_SYS_MALLOC_F for boards which have a non-zero value
for CONFIG_SPL_SYS_MALLOC_F_LEN

Note that the default is yes in most cases, so no changes are needed to
board defconfig options.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-snapdragon/Kconfig b/arch/arm/mach-snapdragon/Kconfig
index 914f4d9..0e07304 100644
--- a/arch/arm/mach-snapdragon/Kconfig
+++ b/arch/arm/mach-snapdragon/Kconfig
@@ -6,6 +6,9 @@
 config SYS_MALLOC_F_LEN
 	default 0x2000
 
+config SPL_SYS_MALLOC_F
+	default y
+
 config SPL_SYS_MALLOC_F_LEN
 	default 0x2000