Adapt make build system

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/Makefile b/library/Makefile
index 8a55328..e965158 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -243,6 +243,7 @@
 
 static: libmbedcrypto.a libmbedx509.a libmbedtls.a
 	cd ../tests && echo "This is a seedfile that contains 64 bytes (65 on Windows)......" > seedfile
+	cd ../tf-psa-crypto/tests && echo "This is a seedfile that contains 64 bytes (65 on Windows)......" > seedfile
 
 shared: libmbedcrypto.$(DLEXT) libmbedx509.$(DLEXT) libmbedtls.$(DLEXT)