tpl: Enable CONFIG_TPL_SYS_MALLOC_F where needed

Enable CONFIG_TPL_SYS_MALLOC_F for boards which have a non-zero value
for CONFIG_TPL_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-rockchip/rv1126/Kconfig b/arch/arm/mach-rockchip/rv1126/Kconfig
index 7382c55..a6e2b59 100644
--- a/arch/arm/mach-rockchip/rv1126/Kconfig
+++ b/arch/arm/mach-rockchip/rv1126/Kconfig
@@ -42,6 +42,9 @@
 config TPL_STACK
         default 0xff718000
 
+config TPL_SYS_MALLOC_F
+	default y
+
 config TPL_SYS_MALLOC_F_LEN
 	default 0x2000