Add required dependency to the testcase

Co-authored-by: Paul Elliott <62069445+paul-elliott-arm@users.noreply.github.com>
Signed-off-by: Jonathan Winzig <jwinzig@hilscher.com>
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index 4c002f9..503d976 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -753,7 +753,7 @@
 }
 /* END_CASE */
 
-/* BEGIN_CASE */
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CSR_WRITE_C */
 void x509_set_extension_length_check()
 {
     int ret = 0;