boot: CONFIG_CEDIT must depend on CONFIG_EXPO

Building sandbox_defconfig with

    CONFIG_CMD_CEDIT=y
    CONFIG_EXPO=n

fails with

    cmd/cedit.c:258:(.text.do_cedit_run+0x4c):
    undefined reference to `expo_apply_theme

Fix the dependencies.

Fixes: a0874dc4ac71 ("expo: Add a configuration editor")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Makefile b/boot/Makefile
index a90ebea..a47e002 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -33,11 +33,11 @@
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_CROS) += bootm.o bootm_os.o bootmeth_cros.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SANDBOX) += bootmeth_sandbox.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SCRIPT) += bootmeth_script.o
+obj-$(CONFIG_$(SPL_TPL_)CEDIT) += cedit.o
 ifdef CONFIG_$(SPL_TPL_)BOOTSTD_FULL
 obj-$(CONFIG_BOOTEFI_BOOTMGR) += bootmeth_efi_mgr.o
 obj-$(CONFIG_$(SPL_TPL_)EXPO) += bootflow_menu.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootflow_menu.o
-obj-$(CONFIG_$(SPL_TPL_)CEDIT) += cedit.o
 endif
 
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += fdt_support.o