Add check for the ecp module variants

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/ecp_new.c b/library/ecp_new.c
index c212f63..3df6f9f 100644
--- a/library/ecp_new.c
+++ b/library/ecp_new.c
@@ -3639,12 +3639,16 @@
 
 #endif /* MBEDTLS_SELF_TEST */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+
 MBEDTLS_STATIC_TESTABLE
 mbedtls_ecp_variant mbedtls_ecp_get_variant()
 {
     return MBEDTLS_ECP_VARIANT_WITH_MPI_UINT;
 }
 
+#endif /* MBEDTLS_TEST_HOOKS */
+
 #endif /* !MBEDTLS_ECP_ALT */
 
 #endif /* MBEDTLS_ECP_LIGHT */