pk: add checks for the returned ECC family

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index d397374..7227f92 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -38,6 +38,10 @@
     size_t key_len;
     int ret;
 
+    if (curve == 0) {
+        return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
+    }
+
     psa_set_key_type(&key_attr, PSA_KEY_TYPE_ECC_KEY_PAIR(curve));
     psa_set_key_bits(&key_attr, curve_bits);
     psa_set_key_usage_flags(&key_attr, PSA_KEY_USAGE_EXPORT);