Add U-Boot x86_64 payload

Currently seems to stall when booted from the GRUB
payload, but works when booted from the SeaBIOS menu.

I also tested it as a standalone payload and it seems
to boot. Will test on hardware next, and start adding
it to more mainboards.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/lib.sh

@@ -213,7 +213,7 @@ cbfs()
 	fAdd="$2" # file to add
 	fName="$3" # filename when added in CBFS
 
-	ccmd="add-payload" && [ $# -gt 3 ] && ccmd="add"
+	ccmd="add-payload" && [ $# -gt 3 ] && [ $# -lt 5 ] && ccmd="add"
 	lzma="-c lzma" && [ $# -gt 3 ] && [ $# -lt 5 ] && lzma="-t $4"
 
 	# hack. TODO: do it better. this whole function is cursed