tests: Remove obsolete MTD support.

Track the change in commit 63a319201fc0f5c34c1c62b446527e06f57f8d40 and
fix builds.

Bug: http://b/29250988
Change-Id: Iad5be953e102020931649629afc980d585ed2931
diff --git a/tests/Android.mk b/tests/Android.mk
index 4509c42..279a6cb 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -46,7 +46,6 @@
 LOCAL_STATIC_LIBRARIES := \
     libapplypatch \
     libotafault \
-    libmtdutils \
     libbase \
     libverifier \
     libcrypto_utils_static \