test_suite_psa_crypto: add test case for ECP conversion with null values

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/suites/test_suite_psa_crypto.data b/tests/suites/test_suite_psa_crypto.data
index 501cbb7..c0916e0 100644
--- a/tests/suites/test_suite_psa_crypto.data
+++ b/tests/suites/test_suite_psa_crypto.data
@@ -7459,6 +7459,9 @@
 depends_on:PSA_WANT_ECC_MONTGOMERY_448
 ecc_conversion_functions:MBEDTLS_ECP_DP_CURVE448:PSA_ECC_FAMILY_MONTGOMERY:448
 
+ECP group ID <-> PSA family - Null values
+ecc_conversion_functions:MBEDTLS_ECP_DP_NONE:0:0
+
 ECP group ID <-> PSA family - Wrong values
 ecc_conversion_functions:MBEDTLS_ECP_DP_MAX:0:0