nvidia-cbootimage: add submodule

Change-Id: I3ad8eed42255db426987065190c197baead40673
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6836
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/.gitmodules b/.gitmodules
index 8702ff0..a7a9d43 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -3,3 +3,6 @@
 	url = ../blobs.git
 	update = none
 	ignore = dirty
+[submodule "util/nvidia-cbootimage"]
+	path = util/nvidia-cbootimage
+	url = ../nvidia-cbootimage.git
diff --git a/util/nvidia-cbootimage b/util/nvidia-cbootimage
new file mode 160000
index 0000000..62a83fa
--- /dev/null
+++ b/util/nvidia-cbootimage
@@ -0,0 +1 @@
+Subproject commit 62a83faac08dba2591c5e188a0c8257dd64c9565