test: unit test for efi_dp_check_length()

Provide a unit test for function efi_dp_check_length().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/test/lib/Makefile b/test/lib/Makefile
index b6a0a20..ada62fe 100644
--- a/test/lib/Makefile
+++ b/test/lib/Makefile
@@ -3,6 +3,7 @@
 # (C) Copyright 2018
 # Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
 obj-y += cmd_ut_lib.o
+obj-$(CONFIG_EFI_LOADER) += efi_device_path.o
 obj-$(CONFIG_EFI_SECURE_BOOT) += efi_image_region.o
 obj-y += hexdump.o
 obj-y += lmb.o