Build: Add MBEDTLS_TARGET_PREFIX

Allows required targets to have prefixes added to them, so that external
projects can avoid target names clashing.

Signed-off-by: Raef Coles <raef.coles@arm.com>
diff --git a/programs/fuzz/CMakeLists.txt b/programs/fuzz/CMakeLists.txt
index e2b0eac..35512c7 100644
--- a/programs/fuzz/CMakeLists.txt
+++ b/programs/fuzz/CMakeLists.txt
@@ -1,5 +1,5 @@
 set(libs
-    mbedtls
+    ${mbedtls_target}
 )
 
 if(USE_PKCS11_HELPER_LIBRARY)