expo: Add support for scene menus

A menu is a key part of the expo design. It consists of a number of items
which the user can select from.

Add the initial implementation of this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Makefile b/boot/Makefile
index f0c3154..0b30fcd 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -47,6 +47,8 @@
 obj-$(CONFIG_SPL_LOAD_FIT) += common_fit.o
 endif
 
+obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += expo.o scene.o scene_menu.o
+
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE) += vbe.o vbe_request.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE_SIMPLE) += vbe_simple.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_VBE_SIMPLE_FW) += vbe_simple_fw.o