upl: Add support for reading a upl handoff

Universal Payload provides a standard way of handing off control between
two firmware phases. Add support for reading the handoff information into
a structure.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Makefile b/boot/Makefile
index dff6f99..9e4e5a6 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -43,6 +43,9 @@
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += fdt_support.o
 obj-$(CONFIG_$(SPL_TPL_)FDT_SIMPLEFB) += fdt_simplefb.o
 
+obj-$(CONFIG_$(SPL_TPL_)UPL) += upl_common.o
+obj-$(CONFIG_$(SPL_TPL_)UPL_READ) += upl_read.o
+
 obj-$(CONFIG_$(SPL_TPL_)OF_LIBFDT) += image-fdt.o
 obj-$(CONFIG_$(SPL_TPL_)FIT_SIGNATURE) += fdt_region.o
 obj-$(CONFIG_$(SPL_TPL_)FIT) += image-fit.o