fdt: Add tests for fdtdec

The fdtdec_find_aliases_for_id() function is complicated enough that
it really should have some tests. This does not necessarily need to be
committed to U-Boot, but it might be useful.

(note there are a few minor inconsistencies with this patch which will be
cleaned up when the USB series is applied)

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/lib/Makefile b/lib/Makefile
index 4b5734a..a0fec60 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -40,6 +40,7 @@
 COBJS-y += display_options.o
 COBJS-y += errno.o
 COBJS-$(CONFIG_OF_CONTROL) += fdtdec.o
+COBJS-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o
 COBJS-$(CONFIG_GZIP) += gunzip.o
 COBJS-y += hashtable.o
 COBJS-$(CONFIG_LMB) += lmb.o