ta: pkcs11: Enforce that helpers are up to date

During each build enforce that src/pkcs11-helpers.c is up to date.

Signed-off-by: Vesa Jääskeläinen <vesa.jaaskelainen@vaisala.com>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jerome Forissier <jerome@forissier.org>

ta/pkcs11/user_ta.mk

@@ -1 +1,8 @@
 user-ta-uuid := fd02c9da-306c-48c7-a49c-bbd827ae86ee
+
+all: pkcs11-ta-verify-helpers
+
+.PHONY: pkcs11-ta-verify-helpers
+pkcs11-ta-verify-helpers:
+	@$(cmd-echo-silent) '  CHK    ' $@
+	${q}ta/pkcs11/scripts/verify-helpers.sh --quiet