programs, tests: Depend only on libmbedcrypto

Update the tests and programs to depend only on libmbedcrypto, since
we'll soon only build libmbedcrypto.
diff --git a/programs/util/CMakeLists.txt b/programs/util/CMakeLists.txt
index f9b6604..4c3fb0d 100644
--- a/programs/util/CMakeLists.txt
+++ b/programs/util/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(libs
-    mbedtls
+    mbedcrypto
 )
 
 add_executable(strerror strerror.c)