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/MAINTAINERS b/MAINTAINERS
index ddcb712..04a6f23 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1709,6 +1709,13 @@
 S:	Maintained
 F:	drivers/ufs/
 
+UPL
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+T:	git https://source.denx.de/u-boot/custodians/u-boot-dm.git
+F:	boot/upl*
+F:	include/upl.h
+
 USB
 M:	Marek Vasut <marex@denx.de>
 S:	Maintained